Optical unit, vehicle monitor, and obstruction detector

ABSTRACT

Disclosed is an optical unit wherein a rotating reflector rotates about a rotation axis in one direction, while reflecting light emitted from a light source. The rotating reflector is provided with a reflecting surface such that the light reflected by the rotating reflector, while rotating, forms a desired light distribution pattern, said light having been emitted from the light source. The light source is composed of light emitting elements. The rotation axis is provided within a plane that includes an optical axis and the light source. The rotating reflector is provided with, on the periphery of the rotation axis, a blade that functions as the reflecting surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2010-092123, filed on Apr. 13,2010, Japanese Patent Application No. 2010-092124, filed on Apr. 13,2010, Japanese Patent Application No. 2010-097946, filed on Apr. 21,2010, Japanese Patent Application No. 2010-110139, filed on May 12,2010, and Japanese Patent Application No. 2011-021905, filed on Feb. 3,2011, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical unit, and more particularly,to an optical unit used for a vehicle lamp. Further, the presentinvention relates to a vehicle monitor. Furthermore, the presentinvention relates to an obstruction detector.

2. Description of the Related Art

In recent years, a vehicle headlight that includes a mirror and canreciprocatively turn the mirror has been known (see Patent Document 1).The mirror reflects light emitted from a light source, which is formedof a plurality of light emitting elements, to the front of a vehicle.The vehicle headlight can scan an illumination region in front of avehicle with light reflected by the mirror that is reciprocativelyturned. The vehicle headlight includes an actuator that makes the mirrorbe reciprocatively turned.

Further, in the past, a method of detecting the light of a lamp of avehicle, which is present on the front, using a camera has been known asa method of detecting a vehicle that travels on the front at night.However, this method has a possibility that the light reflected by areflective object, such as a roadside delineator or a signboard, iserroneously detected as the light of a lamp of a vehicle. Accordingly,there is known a technique that discriminates a lamp of a vehicle, whichis present on the front, from other reflective objects using a fact thatthe brightness of reflected light is changed when the brightness of aheadlamp is reduced (see Patent Document 2).

Furthermore, various methods of detecting vehicles-in-front orpedestrians and obstructions, which are present in front of a vehicle,have been devised in the past. Patent Document 3 discloses a vehicleillumination device that includes an infrared sensor for detecting anobject around a vehicle using infrared light and a visible light sourceirradiating the object with visible light when the infrared sensordetects the object. The vehicle illumination device scans a region infront of the vehicle in a predetermined pattern with infrared light,which is reflected by a reflecting mirror to be reciprocatively turned.

CITATION LIST Patent Document

-   Patent Document 1: JP 2009-224039 A-   Patent Document 2: JP 2001-519744 W-   Patent Document 3: JP 2009-18726 A

However, since the above-mentioned actuator includes a permanent magnetand a coil, there is a restriction on the size of the mirror that can bereciprocatively turned. For this reason, it is difficult to increase aratio of light, which is reflected by the mirror, to the light emittedfrom a light source. Accordingly, there is room for improvement in termsof the efficient use of the light emitted from the light source.

Further, an additional circuit is required in the technique disclosed inPatent Document 2 in order to reduce the brightness of the headlamp, sothat costs are increased. Furthermore, since the brightness of theheadlamp is temporarily changed, a driver may feel discomfort.

Meanwhile, a method using a millimeter-wave radar has been developed asanother method of detecting a vehicle-in-front or the like that ispresent in front of a vehicle. When a normal millimeter-wave radar ismounted on a vehicle to detect an obstruction on the front, noisesreflected by the road surface are increased if the mounting position ofthe normal millimeter-wave radar is excessively low and radarirradiation to an obstruction tends to be reduced if the mountingposition of the normal millimeter-wave radar is excessively high. Forthis reason, a desirable place where the normal millimeter-wave radar isdisposed is limited. Moreover, since the millimeter-wave radar has asize of about 80 mm×80 mm, the millimeter-wave radar needs to bedisposed in consideration of the interference with other components.

SUMMARY OF THE INVENTION

The invention has been made in consideration of these circumstances, andan object of the invention is to provide a technique related to anoptical unit that can efficiently use the light of a light source forillumination.

Further, another object of the invention is to provide a technique thataccurately and easily detects a vehicle traveling on the front at night.

Furthermore, still another object of the invention is to provide atechnique that can dispose an obstruction detector at a suitable place.

To solve the above-mentioned problems, an optical unit according to anaspect of the invention includes a rotating reflector that is rotatedabout a rotation axis in one direction while reflecting light emittedfrom a light source. The rotating reflector is provided with areflecting surface so that the light of the light source reflected bythe rotating reflector while the rotating reflector is rotated forms adesired light distribution pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of examples only, withreference to the accompanying drawings which are meant to be exemplary,not limiting and wherein like elements are numbered alike in severalFigures in which:

FIG. 1 is a horizontal cross-sectional view of a vehicle headlightaccording to this embodiment;

FIG. 2 is a top view schematically showing the structure of a lamp unitthat includes an optical unit according to this embodiment;

FIG. 3 is a side view when the lamp unit is seen in an “A” directionillustrated in FIG. 1;

FIGS. 4( a) to 4(e) are perspective views showing the aspects of bladesthat correspond to the rotation angle of a rotating reflector of thelamp unit according to this embodiment;

FIGS. 5( a) to 5(e) are views showing projection images at scanningpositions where the rotating reflector corresponds to the states ofFIGS. 4( f) to 4(j);

FIG. 6( a) is a view showing a light distribution pattern when a rangeof ±5° on the left and right sides of an optical axis is scanned by thevehicle headlight according to this embodiment, FIG. 6( b) is a viewshowing the light intensity distribution of the light distributionpattern illustrated in FIG. 6( a), FIG. 6( c) is a view showing a statewhere light is blocked at one position on the light distribution patternby the vehicle headlight according to this embodiment, FIG. 6( d) is aview showing the light intensity distribution of the light distributionpattern illustrated in FIG. 6( c), FIG. 6( e) is a view showing a statewhere light is blocked at a plurality of positions on the lightdistribution pattern by the vehicle headlight according to thisembodiment, and FIG. 6( f) is a view showing the light intensitydistribution of the light distribution pattern illustrated in FIG. 6(e);

FIG. 7( a) is a view showing a projection image when light of a LED isreflected by a plane mirror and is projected by an aspherical lens, FIG.7( b) is a view showing a projection image of a vehicle headlightaccording to a first embodiment, and FIG. 7( c) is a view showing aprojection image of a vehicle headlight according to a secondembodiment;

FIG. 8 is a front view of an optical unit according to the secondembodiment;

FIGS. 9( a) to 9(e) are views showing projection images when a rotatingreflector of the optical unit according to the second embodiment isrotated by 30°;

FIG. 10( a) is a perspective view of a light source according to thesecond embodiment, and FIG. 10( b) is a cross-sectional view taken alongline B-B of FIG. 10( a);

FIG. 11( a) is a view showing an irradiation pattern that is formed bythe optical unit according to the second embodiment, and FIG. 11( b) isa view showing a state where the projection images formed by the opticalunit according to the second embodiment are combined;

FIG. 12( a) is a view showing a state where a compound parabolicconcentrator including a LED is disposed so that the longitudinaldirection of the compound parabolic concentrator is parallel to avertical direction, and FIG. 12( b) is a view showing a state where thecompound parabolic concentrator is disposed so that the longitudinaldirection of the compound parabolic concentrator is inclined withrespect to the vertical direction;

FIG. 13( a) is a view showing an irradiation pattern that is formed byan optical unit according to a third embodiment, and FIG. 13( b) is aview showing a state where the projection images formed by the opticalunit according to the third embodiment are combined;

FIG. 14 is a side view schematically showing a lamp unit according to afourth embodiment;

FIG. 15 is a top view schematically showing the lamp unit according tothe fourth embodiment;

FIG. 16 is a view showing a projection image when a rotating reflectoris in the state of FIG. 14;

FIG. 17( a) is a view showing an irradiation pattern that is formed by afront LED, FIG. 17( b) is a view showing an irradiation pattern that isformed by a rear LED, and FIG. 17( c) is a view showing a combined lightdistribution pattern that is formed by two LEDs;

FIG. 18( a) is a view showing an irradiation pattern that is formed bythe front LED and includes a light blocking portion, FIG. 18( b) is aview showing an irradiation pattern that is formed by the rear LED andincludes a light blocking portion, and FIG. 18( c) is a view showing acombined light distribution pattern that is formed by two LEDs andincludes a light blocking portion;

FIG. 19 is a top view schematically showing the structure that includesan optical unit according to a fifth embodiment;

FIG. 20 is a view schematically showing a light distribution patternthat is formed by a vehicle headlight including the optical unitaccording to the fifth embodiment;

FIG. 21( a) is a view showing light distribution patterns that areformed by the respective light sources, and FIGS. 21( b) to 21(f) areviews showing irradiation patterns that are formed by the respective LEDunits;

FIG. 22( a) is a perspective view of the LED unit according to the fifthembodiment, FIG. 22( b) is a cross-sectional view taken along line C-Cof FIG. 22( a), and FIG. 22( c) is a cross-sectional view taken alongline D-D of FIG. 22( a);

FIG. 23( a) is a view showing a light distribution pattern that isformed by the respective light sources and includes a light blockingportion, and FIGS. 23( b) to 23(f) are views showing irradiationpatterns that are formed by the respective LED units and include lightblocking portions;

FIG. 24 is a perspective view of a rotating reflector according to asixth embodiment;

FIG. 25( a) is a view showing an ideal irradiation pattern when theshapes of the respective blades are completely the same, and FIG. 25( b)is a view showing an irradiation pattern when there is an error in theshape of each of the blades;

FIG. 26 is a perspective view of a rotating reflector according to amodification of the sixth embodiment;

FIG. 27 is a side view of the rotating reflector illustrated in FIG. 26;

FIG. 28 is a top view schematically showing the structure that includesan optical unit according to the sixth embodiment;

FIG. 29 is a view showing the disposition of the rotating reflectoraccording to the modification;

FIG. 30 is a block diagram of a vehicle monitor according to a seventhembodiment;

FIG. 31 is a view schematically showing a state where a partial region(a middle region in front of a vehicle) included in alight distributionpattern is irradiated with an irradiation beam;

FIG. 32 is a view schematically showing a state where a partial region(the middle region in front of the vehicle) included in a lightdistribution pattern is not irradiated with an irradiation beam;

FIG. 33 is a flowchart illustrating the processing for determining areflective body according to the seventh embodiment;

FIG. 34 is a view illustrating a state where light is blocked on a partof a high beam-light distribution pattern;

FIG. 35 is a view schematically illustrating an irradiation position andimaging timing;

FIG. 36 is a view schematically illustrating a condition where the sameregion of a continuous taken image is not continuously irradiated;

FIG. 37 is a schematic view showing the entire structure of a vehicleheadlight according to an eighth embodiment;

FIG. 38 is a perspective view showing a mirror unit and a light sourceunit;

FIG. 39 is a view schematically showing the combination of a lightsource, an optical system for shaping, and a mirror;

FIG. 40 is a view schematically showing a state where a partial regionincluded in a light distribution pattern is irradiated with twoirradiation beams;

FIG. 41 is a top view schematically showing an obstruction detectoraccording to a tenth embodiment;

FIG. 42( a) is a view schematically showing the focal length of amillimeter wave and the focal length of visible light when a projectionlens is made of polycarbonate, and FIG. 42( b) is a view schematicallyshowing the focal length of a millimeter wave and the focal length ofvisible light when a projection lens is made of acrylic; and

FIG. 43 is a schematic view of a millimeter-wave radar according to amodification.

DETAILED DESCRIPTION OF THE INVENTION

To solve the above-mentioned problems, an optical unit according to anaspect of the invention includes a rotating reflector that is rotatedabout a rotation axis in one direction while reflecting light emittedfrom a light source. The rotating reflector is provided with areflecting surface so that the light of the light source reflected bythe rotating reflector while the rotating reflector is rotated forms adesired light distribution pattern.

According to this aspect, since it is possible to form a desired lightdistribution pattern by the rotation of the rotating reflector in onedirection, drive using a special mechanism such as a resonance mirror isnot needed and there is less restriction on the size of the reflectingsurface unlike in the resonance mirror. For this reason, it is possibleto efficiently use the light, which is emitted from the light source,for illumination by selecting a rotating reflector that has a largerreflecting surface.

The optical unit may further include a light source that is formed of alight emitting element. The rotation axis may be provided on a planethat includes the optical axis and the light source. Furthermore, therotation axis may be provided substantially parallel to a scan plane ofan irradiation beam that performs scanning in a left and right directionby rotation. Accordingly, the thickness of the optical unit is reduced.Here, substantially parallel may mean virtually parallel and does notneed to mean perfectly parallel. This is to allow an error in a rangethat does not significantly suppress the effect of an optical unitaccording to a certain aspect.

The rotating reflector includes blades that function as the reflectingsurface and are provided around the rotation axis, and the blades have atwisted shape so that an angle between an optical axis and thereflecting surface is changed in a circumferential direction having acenter on the rotation axis. Thus, the scanning with use of the light ofthe light source becomes possible.

The optical unit may further include a plurality of blades that arearranged in a circumferential direction of the rotation axis, andpartition members that are provided between the adjacent blades andextend in a direction of the rotation axis. The partition members may beformed so as to suppress the incidence of the light emitted from thelight source upon the reflecting surface of the other adjacent bladewhen the light emitted from the light source enters the reflectingsurface of one adjacent blade. When light simultaneously enters both theadjacent blades, both end portions of a light distribution pattern shineat the same time. In this case, it is difficult to independently controlthe irradiation states of both the end portions of the lightdistribution pattern. Accordingly, the light sources are turned off atthe timing where light simultaneously enters both the adjacent blades,so that both the end portions of the light distribution pattern cannotbe simultaneously irradiated. Meanwhile, if the light sources aretemporarily turned off at the above-mentioned timing, the brightness ofboth the end portions of the light distribution pattern is reduced tosome extent. Accordingly, since the above-mentioned partition membersare provided between the adjacent blades, it is possible to block thelight, which is directed to the end portion of the adjacent blade, ofthe light, which is emitted from the light source irradiating the endportion of one blade, to some extent. That is, since the time, whichpasses while light simultaneously enters both the adjacent blades, isshortened, it is also possible to correspondingly shorten the time thatpasses while the light source is turned off.

The optical unit may further include a projection lens that projects thelight reflected by the rotating reflector in a light irradiationdirection of the optical unit. The projection lens may correct an imageof the light source distorted by being reflected on the reflectingsurface to a shape close to the shape of the light source itself. Thus,a desired region can be accurately irradiated.

The light source may include a rectangular light emitting surface, andeach side of the light emitting surface may be inclined with respect toa vertical direction so that an image of the light source projectedforward by the projection lens is substantially erected. Thus, astructure for correcting the image of the light source can besimplified.

The optical unit may further include a plurality of light sources thatare formed of light emitting elements. The plurality of light sourcesmay be disposed so that light emitted from the respective light sourcesis reflected at different positions on the reflecting surface.Accordingly, it is possible to form a plurality of light distributionpatterns and to form new light distribution patterns by combining theselight distribution patterns. Therefore, it is easier to design an ideallight distribution pattern.

The optical unit may further include: a first projection lens thatprojects light, which is emitted from one light source of the pluralityof light sources and reflected by the rotating reflector, in a lightirradiation direction of the optical unit as a first light distributionpattern; and a second projection lens that projects light, which isemitted from the other light source of the plurality of light sourcesand reflected by the rotating reflector, in the light irradiationdirection of the optical unit as a second light distribution pattern.Thus, by appropriately selecting the projection lens, different lightdistribution patterns can be formed by one rotating reflector.

The light source may include a light concentrating member where a lightemitting element is disposed on a bottom and a rectangular openingportion is formed. The light concentrating member may include lightconcentrating surfaces that are formed from the bottom toward theopening portion in order to concentrate the light of the light emittingelement. The light concentrating surfaces may be formed so that theheights of end portions of the opening portion in a longitudinaldirection of the opening portion are higher than the heights of endportions of the opening portion in a width direction of the openingportion. Accordingly, it is possible to suppress the generation ofdiffused light, which does not reach the reflecting surface of therotating reflector, of the light of the light emitting element.

The optical unit may be formed so as to be used for a vehicle lamp.

Another aspect of the invention is also an optical unit. The opticalunit according to this aspect of the invention is used for a vehiclelamp, and includes: a heat dissipation part that radiates heat of alight source; and a cooling fan. The cooling fan includes blades thatform a light distribution pattern by reflecting light, which is emittedfrom the light source, forward and causes convection near the heatdissipation part.

According to this aspect, since it is possible to form a desired lightdistribution pattern using a cooling fan, drive using a specialmechanism such as a resonance mirror is not needed and there is lessrestriction on the size of the reflecting surface unlike in theresonance mirror. For this reason, it is possible to efficiently use thelight, which is emitted from the light source, for illumination byselecting a cooling fan that has a larger blade. Further, since areflector does not need to be provided separately from the cooling fan,it is possible to simplify the structure of the optical unit.

Another aspect of the invention is a vehicle monitor. The vehiclemonitor according to this aspect of the invention includes: an opticalunit that forms a light distribution pattern by scanning an irradiationbeam to the front of a vehicle; a camera that takes an image of a regionin front of the vehicle; and a determining device that determineswhether a reflective body reflecting the irradiation beam is present ina partial region on the basis of an image that is taken by the camerawhen the partial region included in the light distribution pattern isirradiated with the irradiation beam and an image that is taken by thecamera when the partial region is not irradiated with the irradiationbeam.

Still another aspect of the invention is also a vehicle monitor. Thevehicle monitor according to this aspect of the invention includes: aplurality of optical units that form a light distribution pattern byscanning irradiation beams to the front of a vehicle; a camera thattakes an image of a region in front of the vehicle; and a determiningdevice that determines whether a reflective body reflecting theirradiation beam is present in a partial region on the basis of an imagethat is taken by the camera when the partial region included in thelight distribution pattern is irradiated with the irradiation beam andan image that is taken by the camera when the partial region is notirradiated with the irradiation beam.

According to this aspect, not only a lamp of a vehicle that is presenton the front but also a reflective body that reflects the irradiationbeam can be detected from the image that is taken by the camera when thepartial region included in the light distribution pattern is irradiatedwith the irradiation beam. Meanwhile, a lamp of a vehicle that ispresent on the front can be detected from the image that is taken by thecamera when the partial region is not irradiated with the irradiationbeam, but a reflective body not irradiated with the irradiation beam isnot detected. Accordingly, whether a reflective body is present in apartial region can be determined through the comparison between theimage that is taken when the partial region is irradiated with anirradiation beam and the image that is taken when the partial region isnot irradiated with an irradiation beam.

The optical unit may scan an irradiation beam so that a regionirradiated with an irradiation beam varies at each of the timing ofplural times of imaging that are performed by the camera.

Each of the plurality of optical units may scan an irradiation beam sothat a region irradiated with irradiation beams varies at each of thetiming of plural times of imaging that are performed by the camera.

Assuming that the number of times of scanning of a first optical unit ofthe plurality of optical units is represented by A1 (times/s), thenumber of times of scanning of a second optical unit of the plurality ofoptical units is represented by A2 (times/s), the number of times ofimaging of the camera is represented by D (times/s), and m and n arenatural numbers, the following expressions (1) and (2) may be satisfied:

mD<A1<(m+0.5)D or (m+0.5)D<A1<(m+1)D  Expression (1)

nD<A2<(n+0.5)D or (n+0.5)D<A2<(n+1)D  Expression (2).

Accordingly, it is possible to take an image when a certain region isirradiated with an irradiation beam and an image when the certain regionis not irradiated with an irradiation beam.

Assuming that the number of times of scanning of the optical unit isrepresented by A [times/s], scanning speed is represented by B [deg/s],the width of an irradiation beam is represented by C [deg], and thenumber of times of imaging of the camera is represented by D [times/s],an expression C≦(decimal part of A/D)×(B/A)≦(B/A)−C may be satisfied.Accordingly, it is possible to take an image when a certain region isirradiated with an irradiation beam and an image when the certain regionis not irradiated with an irradiation beam.

The optical unit may include a rotating reflector that is rotated abouta rotation axis in one direction while reflecting light emitted from alight source. The rotating reflector may be provided with a reflectingsurface so that the light of the light source reflected by the rotatingreflector while the rotating reflector is rotated forms a desired lightdistribution pattern. Accordingly, it is possible to form a desiredlight distribution pattern by the rotation of the rotating reflector inone direction. Further, it is possible to efficiently use the light,which is emitted from the light source, for illumination by selecting arotating reflector that has a larger reflecting surface.

The vehicle monitor may further include a controller that controls therotational speed of the rotating reflector. Accordingly, it is possibleto easily change the rotational speed of the rotating reflector to anappropriate value considering the imaging timing of the camera.

The optical unit may include a rotating reflector that is rotated abouta rotation axis in one direction while reflecting light emitted from alight source. The rotating reflector may be provided with a reflectingsurface so that the light of the light source reflected by the rotatingreflector while the rotating reflector is rotated forms a desired lightdistribution pattern. Accordingly, it is possible to form a desiredlight distribution pattern by the rotation of the rotating reflector inone direction. Further, it is possible to efficiently use the light,which is emitted from the light source, for illumination by selectingthe rotating reflector that has a larger reflecting surface.

Another aspect of the invention is an obstruction detector. Theobstruction detector according to this aspect of the invention includes:an invisible-light radar; a rotating reflector that is rotated about arotation axis in one direction while reflecting invisible light sentfrom the invisible-light radar; and a projection lens that focuses theinvisible light reflected by the rotating reflector and projects theinvisible light to a surrounding region. The rotating reflector isprovided with a reflecting surface so that a surrounding region isscanned with the invisible light reflected by the rotating reflectorwhile the rotating reflector is rotated.

According to this aspect, since it is possible to scan the surroundingregion with invisible light by the operation of the rotating reflector,it is possible to simplify the structure of the invisible-light radar.Accordingly, it is possible to dispose an obstruction detector at asuitable place. Here, the surrounding region is a region around a placewhere the obstruction detector is installed. For example, when theobstruction detector is installed in a vehicle, the front, the rear, theside, and the like of the vehicle are included in the surroundingregion.

The obstruction detector may further include a light source that isformed of a light emitting element. The rotating reflector may beprovided with a reflecting surface so as to form a desired lightdistribution pattern in front of a vehicle by reflecting light emittedfrom the light source while being rotated. Furthermore, the projectionlens may project the light, which is reflected by the rotatingreflector, in a light irradiation direction. Accordingly, it is possibleto achieve the scanning using invisible light and the formation of alight distribution pattern by the operation of the rotating reflector.

The invisible-light radar may be a millimeter-wave radar. The lightsource may be provided so that the position of a virtual image formed bythe rotating reflector is positioned near a focal point of theprojection lens corresponding to visible light. The millimeter-waveradar may be provided so that the position of a virtual image formed bythe rotating reflector is positioned near a focal point of theprojection lens corresponding to a millimeter wave that is differentfrom the focal point of the projection lens corresponding to visiblelight. Accordingly, the millimeter-wave radar and the light source canbe disposed at the positions of the focal points suitable thereforwithout interfering with each other.

The millimeter-wave radar may include a waveguide, and the waveguide maybe provided so that the position of a virtual image of an end portion ofthe waveguide formed by the rotating reflector is positioned closer tothe projection lens than the focal point corresponding to visible light.Accordingly, for example, the receiving part and the sending part of themillimeter-wave radar can be disposed more distant from the projectionlens than the light source. As a result, light, which is directed to theprojection lens from the light source, is prevented from being blockedby the receiving part and the sending part.

The projection lens may be made of a resin material. Accordingly, theweight of the obstruction detector is reduced. Further, it is possibleto efficiently transmit millimeter waves.

Meanwhile, the arbitrary combination of the above-mentioned components,the changes of the expression of the invention into a method, a device,a system, and the like are effective as aspects of the invention.

The invention will be described below on the basis of embodiments withreference to the drawings. The same or equivalent components, members,and processing illustrated in the respective drawings are denoted by thesame reference numeral, and the repeated description thereof will not berepeated. Further, the embodiments are illustrative without limiting theinvention, and all characteristics described in the embodiments or thecombination thereof may not be necessarily essential in the invention.

An optical unit of the invention may be used for various vehicle lamps.A case where the optical unit of the invention is applied to a vehicleheadlight among vehicle lamps will be described below.

First Embodiment

FIG. 1 is a horizontal cross-sectional view of a vehicle headlightaccording to this embodiment. A vehicle headlight 10 is a rightheadlight that is mounted on the right side of the front end portion ofan automobile, and has the same structure as a headlight mounted on theleft side except that the vehicle headlight 10 is symmetrical to theheadlight mounted on the left side. For this reason, in the followingdescription, the right vehicle headlight 10 will be described in detailand the description of the left vehicle headlight will not be described.

As illustrated in FIG. 1, the vehicle headlight 10 includes a lamp body12 that includes a recess opened forward. A front opening of the lampbody 12 is covered with a transparent front cover 14, so that a lampchamber 16 is formed. The lamp chamber 16 functions as a space in whichtwo lamp units 18 and 20 are received so as to be disposed side by sidein the width direction of a vehicle.

Among these lamp units, an outer lamp unit, that is, the lamp unit 20 ofthe right vehicle headlight 10 that is disposed on the upper side inFIG. 1 is a lamp unit including a lens, and is adapted to emit avariable high beam. Meanwhile, among these lamp units, an inner lampunit, that is, the lamp unit 18 of the right vehicle headlight 10 thatis disposed on the lower side in FIG. 1 is adapted to emit a low beam.

The lamp unit 18 for a low beam includes a reflector 22, a light sourcebulb (incandescent bulb) 24 that is supported by the reflector 22, and ashade (not illustrated). The reflector 22 is supported so as to betiltable with respect to the lamp body 12 by known means (notillustrated), for example, means using an aiming screw and a nut.

As illustrated in FIG. 1, the lamp unit 20 includes a rotating reflector26, a LED 28, and a convex lens 30 as a projection lens that is disposedin front of the rotating reflector 26. Meanwhile, a semiconductor lightemitting element, such as an EL element or a LD element, instead of theLED 28 may be used as a light source. In particular, it is preferablethat alight source capable of being accurately turned on/off in a shorttime be used in the control for blocking light on a part of a lightdistribution pattern to be described below. The shape of the convex lens30 may be appropriately selected according to light distributioncharacteristics, such as required light distribution pattern orilluminance distribution. However, an aspherical lens or a freecurved-surface lens may be used. In this embodiment, an aspherical lensis used as the convex lens 30.

The rotating reflector 26 is rotated about a rotation axis R as a centerin one direction by a drive source such as a motor (not illustrated).Further, the rotating reflector 26 includes a reflecting surface that isadapted to form a desired light distribution pattern by reflecting thelight emitted from the LED 28 while being rotated. In this embodiment,the rotating reflector 26 forms an optical unit.

FIG. 2 is a top view schematically showing the structure of the lampunit 20 that includes the optical unit according to this embodiment.FIG. 3 is a side view when the lamp unit 20 is seen in an “A” directionillustrated in FIG. 1.

The rotating reflector 26 includes three blades 26 a that function asthe reflecting surface, have the same shape, and are provided around acylindrical rotating part 26 b. The rotation axis R of the rotatingreflector 26 is inclined with respect to an optical axis Ax, and isprovided in a plane that includes the optical axis Ax and the LED 28. Inother words, the rotation axis R is provided substantially parallel to ascan plane of light (irradiation beam) of the LED 28 that performsscanning in a left and right direction by rotation. Accordingly, thethickness of the optical unit is reduced. Here, the scan plane may be afan-shaped plane that is formed by continuously connecting thetrajectories of light of the LED 28 that is, for example, scanninglight. Further, the LED 28 of the lamp unit 20 according to thisembodiment is relatively small, and the position of the LED 28 is alsodisposed between the rotating reflector 26 and the convex lens 30 andshifted from the optical axis Ax. For this reason, it is possible tomake the vehicle headlight 10 short in a depth direction (thelongitudinal direction of the vehicle) as compared to a case where alight source, a reflector, and a lens are arranged in a line on anoptical axis as in a projector type lamp unit in the related art.

Furthermore, the shapes of the blades 26 a of the rotating reflector 26are formed so that a secondary light source of the LED 28 formed byreflection is formed in the vicinity of the focal point of the convexlens 30. Moreover, the blades 26 a have a twisted shape so that an anglebetween the optical axis Ax and the reflecting surface is changed in thecircumferential direction having a center on the rotation axis R.Accordingly, scanning using the light of the LED 28 can be performed asillustrated in FIG. 2. This will be described in more detail.

FIGS. 4( a) to 4(e) are perspective views showing the aspects of theblades that correspond to the rotation angle of the rotating reflector26 of the lamp unit according to this embodiment. FIGS. 4( f) to 4(j)are views illustrating that a direction where the light emitted from thelight source is reflected is changed according to the states of FIGS. 4(a) to 4(e).

FIG. 4( a) shows a state where the LED 28 is disposed so as to irradiatea boundary region between two blades 26 a 1 and 26 a 2. In this state,the light of the LED 28 is reflected in a direction, which is inclinedwith respect to the optical axis Ax, by a reflecting surface S of theblade 26 a 1 as illustrated in FIG. 4( f). As a result, one end portionregion of both left and right end portions of a region in front of thevehicle where a light distribution pattern is formed is irradiated.After that, when the rotating reflector 26 is rotated and is in thestate illustrated in FIG. 4( b), the reflecting surface S of the blade26 a 1 reflecting the light of the LED 28 (the angle of reflection) ischanged since the blade 26 a 1 is twisted. As a result, the light of theLED 28 is reflected in a direction that is closer to the optical axis Axthan the reflection direction illustrated in FIG. 4( f) as illustratedin FIG. 4( g).

Subsequently, when the rotating reflector 26 is rotated as illustratedin FIGS. 4( c), 4(d), and 4(e), the reflection direction of the light ofthe LED 28 is changed toward the other end portion of both the left andright end portions of the region in front of the vehicle where the lightdistribution pattern is formed. The rotating reflector 26 according tothis embodiment is adapted to be capable of scanning the front region inone direction (horizontal direction) one time with the light of the LED28 by being rotated by 120°. In other words, one blade 26 a passes infront of the LED 28, so that a desired region in front of the vehicle isscanned one time with the light of the LED 28. Meanwhile, as illustratedin FIGS. 4( f) to 4(j), the secondary light source (the virtual image ofa light source) 32 is moved to the left and right near the focal pointof the convex lens 30. The number or shapes of the blades 26 a and therotational speed of the rotating reflector 26 are appropriately set onthe basis of the results of experiments or simulations in considerationof the characteristics of a required light distribution pattern or theflicker of an image to be scanned. Further, a motor is preferable as adrive part that may change rotational speed according to various kindsof control of light distribution. Accordingly, it is possible to easilychange scanning timing. A motor, from which rotation timing informationis obtained, is preferable as such a motor. Specifically, a DC brushlessmotor is used as the motor. Since rotation timing information isobtained from a motor when the DC brushless motor is used, a device suchas an encoder may be omitted.

The rotating reflector 26 according to this embodiment can scan a regionin front of the vehicle in the left and right direction with the lightof the LED 28 through the devising of the shape or rotational speed ofthe blade 26 a as described above. FIGS. 5( a) to 5(e) are views showingprojection images at scanning positions where the rotating reflectorcorresponds to the states of FIGS. 4( f) to 4(j). The units of avertical axis and a horizontal axis in FIGS. 5( a) to 5(e) are degree(°), and the vertical axis and the horizontal axis represent anirradiation range and an irradiation position. As illustrated in FIGS.5( a) to 5(e), the projection images are moved in the horizontaldirection by the rotation of the rotating reflector 26.

FIG. 6( a) is a view showing a light distribution pattern when a rangeof ±5° on the left and right sides of the optical axis is scanned by thevehicle headlight according to this embodiment, FIG. 6( b) is a viewshowing the light intensity distribution of the light distributionpattern illustrated in FIG. 6( a), FIG. 6( c) is a view showing a statewhere light is blocked at one position on the light distribution patternby the vehicle headlight according to this embodiment, FIG. 6( d) is aview showing the light intensity distribution of the light distributionpattern illustrated in FIG. 6( c), FIG. 6( e) is a view showing a statewhere light is blocked at a plurality of positions on the lightdistribution pattern by the vehicle headlight according to thisembodiment, and FIG. 6( f) is a view showing the light intensitydistribution of the light distribution pattern illustrated in FIG. 6(e).

As illustrated in FIG. 6( a), the vehicle headlight 10 according to thisembodiment can form a high beam-light distribution pattern, which islong substantially in the horizontal direction, by reflecting the lightof the LED 28 with the rotating reflector 26 and scanning the frontregion by the reflected light. Since it is possible to form a desiredlight distribution pattern by the rotation of the rotating reflector 26in one direction as described above, drive using a special mechanismsuch as a resonance mirror is not needed and there is less restrictionon the size of the reflecting surface unlike in the resonance mirror.For this reason, it is possible to efficiently use the light, which isemitted from the light source, for illumination by selecting therotating reflector 26 that has a larger reflecting surface. That is, itis possible to increase the maximum light intensity of the lightdistribution pattern. Meanwhile, the diameter of the rotating reflector26 according to this embodiment is substantially the same as thediameter of the convex lens 30, and the area of the blade 26 a can alsobe increased according to the diameter of the rotating reflector 26.

Further, the vehicle headlight 10, which includes the optical unitaccording to this embodiment, can form high beam-light distributionpatterns on which light is blocked in arbitrary regions as illustratedin FIGS. 6( c) and 6(e) by synchronizing the change of the intensity ofemitted light or the turning-on/off timing of the LED 28 with therotation of the rotating reflector 26. Furthermore, when the intensityof emitted light of the LED 28 is changed (the LED 28 is turned on/off)in synchronization with the rotation of the rotating reflector 26 sothat a high beam-light distribution pattern is formed, it is alsopossible to perform a control for swiveling a light distribution patternitself by shifting the phase of change of light intensity.

As described above, the vehicle headlight according to this embodimentcan form a light distribution pattern by scanning the light of the LEDand can arbitrarily form light blocking portions at a part of the lightdistribution pattern by controlling the change of the intensity ofemitted light. For this reason, it is possible to accurately block lightin desired regions by a small number of LEDs as compared to a case wherea part of a plurality of LEDs are turned off to form light blockingportions. Moreover, since the vehicle headlight 10 can form a pluralityof light blocking portions, it is possible to block light in the regionscorresponding to the respective vehicles even when a plurality ofvehicles is present in the front region.

Further, since the vehicle headlight 10 can control the blocking oflight without moving a light distribution pattern that forms a base, itis possible to reduce the discomfort that is felt by a driver at thetime of the control of the blocking of light. Furthermore, since it ispossible to swivel a light distribution pattern without moving the lampunit 20, it is possible to simplify the mechanism of the lamp unit 20.For this reason, the vehicle headlight 10 only has to include a motor,which is required for the rotation of the rotating reflector 26, as adrive part for variable control of light distribution. Accordingly, thevehicle headlight is simplified in structure and is reduced in cost andsize.

Moreover, the LED 28 is disposed in front of the rotating reflector 26according to this embodiment as illustrated in FIGS. 1 and 2, and therotating reflector 26 according to this embodiment functions as acooling fan that sends air to the LED 28. For this reason, a cooling fanand a rotating reflector do not need to be separately provided, so thatit is possible to simplify the structure of the optical unit. Further,since the LED 28 is cooled with the air sent by the rotating reflector26, a heat sink for cooling the LED 28 can be omitted or reduced insize. Accordingly, the optical unit is reduced in size, cost, andweight.

Meanwhile, such a cooling fan may not necessarily have a function ofdirectly sending air to the light source, and may cause convection on aheat dissipation part such as a heat sink. For example, the dispositionof the rotating reflector 26 or a heat sink may be set so that the airsent by the rotating reflector 26 cools the LED 28 by causing convectionnear the heat dissipation part such as a heat sink provided separatelyfrom the LED 28. Meanwhile, the heat dissipation part may be not only aseparate member such as a heat sink but also a part of a light source.

Second Embodiment

When the light of a LED is reflected and is projected forward by aprojection lens, the shape of a projection image does not necessarilycorrespond to the shape of a light emitting surface of the LED. FIG. 7(a) is a view showing a projection image when the light of the LED isreflected by a plane mirror and is projected by an aspherical lens, FIG.7( b) is a view showing a projection image of the vehicle headlightaccording to the first embodiment, and FIG. 7( c) is a view showing aprojection image of a vehicle headlight according to a secondembodiment.

If a reflecting surface is a flat surface, a projection image is similarto the shape of the light emitting surface of the LED as illustrated inFIG. 7( a). However, since the blades 26 a forming the reflectingsurface are twisted in the rotating reflector 26 according to the firstembodiment, a projection image is distorted as illustrated in FIG. 7(b). Specifically, in the first embodiment, the projection image isblurred (an irradiation range is widened) and inclined. For this reason,there are cases where the shape of a light blocking portion or a lightdistribution pattern, which is formed through the scanning of theprojection image, is inclined and a boundary between the light blockingportion and an irradiated portion does not becomes clear.

Accordingly, in the second embodiment, an optical unit is adapted tocorrect an image distorted by being reflected on a curved surface.Specifically, a free curved-surface lens is used as a convex lens in thevehicle headlight according to the second embodiment. FIG. 8 is a frontview of the optical unit according to the second embodiment.

The optical unit according to the second embodiment includes a rotatingreflector 26 and a projection lens 130. The projection lens 130 projectsthe light, which is reflected by the rotating reflector 26, in the lightirradiation direction of the optical unit. The projection lens 130 is afree curved-surface lens that corrects an image of the LED, distorted bybeing reflected on the reflecting surface of the rotating reflector 26,to a shape close to the shape of the light source itself (the shape of alight emitting surface of the LED). The shape of the free curved-surfacelens may be appropriately designed according to the twist or shape ofthe blade. According to the optical unit of this embodiment, asillustrated in FIG. 7( c), the distorted image of the LED is correctedto a shape close to a rectangular shape that is the shape of the lightsource. Further, the maximum light intensity of a projection image,which is formed by the optical unit according to the first embodiment,is 100000 cd (see FIG. 7( b)), but the maximum light intensity of aprojection image, which is formed by the optical unit according to thesecond embodiment, is increased to 146000 cd.

FIGS. 9( a) to 9(e) are views showing projection images when a rotatingreflector of the optical unit according to the second embodiment isrotated by 30°. Since a projection image, which is less blurred than theprojection image of the first embodiment, is formed as illustrated inFIGS. 9( a) to 9(e), it is possible to accurately irradiate a desiredregion with bright light.

Meanwhile, since the light emitted from the LED 28 is wide as it is,there is a case where a part of the light is wasted without beingreflected by the rotating reflector 26. Moreover, even though the lightis reflected by the rotating reflector 26, the resolution of the lightblocking portion tends to be reduced if the size of the projection imageis increased. Accordingly, a light source of this embodiment includesthe LED 28 and a compound parabolic concentrator (CPC) 32 thatconcentrates the light of the LED 28. FIG. 10( a) is a perspective viewof the light source according to the second embodiment, and FIG. 10( b)is a cross-sectional view taken along line B-B of FIG. 10( a).

The compound parabolic concentrator 32 is a box-shaped concentratorwhere the LED 28 is disposed on the bottom. Four side surfaces of thecompound parabolic concentrator 32 are subjected to mirror-finishing soas to have the shape of a parabola that has a focal point on the LED 28or in a region near the LED 28. Accordingly, the light emitted from theLED 28 is concentrated and emitted forward. In this case, a rectangularopening portion 32 a of the compound parabolic concentrator 32 may beconsidered as the light emitting surface of a light source.

Third Embodiment

The optical unit according to the second embodiment can correct theshape of the projection image to a shape close to a rectangular shape,which is the shape of a light source, by the function of the freecurved-surface lens. However, when a light distribution pattern isformed through the scanning of the projection image corrected in thisway, there is still room for improvement.

FIG. 11( a) is a view showing an irradiation pattern that is formed bythe optical unit according to the second embodiment, and FIG. 11( b) isa view showing a state where the projection images formed by the opticalunit according to the second embodiment are combined. FIG. 12( a) is aview showing a state where a compound parabolic concentrator 32including the LED 28 is disposed so that the longitudinal direction ofthe compound parabolic concentrator 32 is parallel to a verticaldirection, and FIG. 12( b) is a view showing a state where the compoundparabolic concentrator 32 is disposed so that the longitudinal directionof the compound parabolic concentrator 32 is inclined with respect tothe vertical direction.

When the light source is in the state illustrated in FIG. 12( a), theirradiation pattern is inclined with respect to a horizontal line byabout 10° as illustrated in FIG. 11( a). Further, when the light sourceis in the state illustrated in FIG. 12( a), each of the projectionimages is inclined with respect to a vertical line by about 20° asillustrated in FIG. 11( b). Accordingly, a structure for correcting theinclination of the irradiation pattern and the projection images will bedescribed in this embodiment.

First, it is possible to correct the inclination of the irradiationpattern by rotating the entire optical system, which includes theprojection lens 130 (see FIG. 8) formed of a free curved-surface lens,the rotating reflector 26, and the LED 28, about the optical axis by10°. Further, it is possible to correct the inclination of each of theprojection images by inclining the light source that includes the LED 28and the compound parabolic concentrator 32. Specifically, each of thesides of the light emitting surface of the light source is inclined withrespect to the vertical direction by 20° as illustrated in FIG. 12( b)so that a projection image projected forward by the projection lens 130is substantially erected.

FIG. 13( a) is a view showing an irradiation pattern that is formed byan optical unit according to a third embodiment, and FIG. 13( b) is aview showing a state where the projection images formed by the opticalunit according to the third embodiment are combined. The inclination ofthe irradiation pattern or each of the projection images is corrected asillustrated in FIG. 13, so that it is possible to form an ideal lightdistribution pattern. Moreover, since it is possible to correct theirradiation pattern and the projection images by inclining the entireoptical system that includes the projection lens 130, the LED 28, andthe rotating reflector 26, it is easy to perform adjustment to obtain adesired light distribution pattern.

Fourth Embodiment

As in the optical units of the above-mentioned embodiments, it ispossible to form a high beam-light distribution pattern by one lightsource. However, there are also considered a case where a brighterirradiation pattern is needed and a case where a LED having low lightintensity is used for the reduction of cost. Accordingly, an opticalunit including a plurality of light sources will be described in thisembodiment.

FIG. 14 is a side view schematically showing a lamp unit according to afourth embodiment. FIG. 15 is a top view schematically showing the lampunit according to the fourth embodiment. The lamp unit 120 according tothe fourth embodiment includes a projection lens 130, a rotatingreflector 26, and two LEDs 28 a and 28 b. FIG. 16 is a view showing aprojection image when the rotating reflector 26 is in the state of FIG.14. A projection image Ia is formed by the light of the LED 28 a that isdisposed on the front side close to the projection lens 130, and aprojection image Ib is formed by the light of the LED 28 b that isdisposed on the rear side distant from the projection lens 130.

FIG. 17( a) is a view showing an irradiation pattern that is formed bythe front LED 28 a, FIG. 17( b) is a view showing an irradiation patternthat is formed by the rear LED 28 b, and FIG. 17( c) is a view showing acombined light distribution pattern that is formed by two LEDs. Asillustrated in FIG. 17( c), it is possible to form a desired lightdistribution pattern even though a plurality of LEDs are used. Further,the maximum light intensity, which is hardly achieved by one LED, isachieved in the combined light distribution pattern.

Next, a case where a light blocking portion is formed in the lightdistribution pattern by the lamp unit 120 will be described. FIG. 18( a)is a view showing an irradiation pattern that is formed by the front LED28 a and includes a light blocking portion, FIG. 18( b) is a viewshowing an irradiation pattern that is formed by the rear LED 28 b andincludes a light blocking portion, and FIG. 18( c) is a view showing acombined light distribution pattern that is formed by the two LEDs andincludes a light blocking portion. For the formation of the lightdistribution patterns illustrated in FIGS. 18( a) and 18(b), theturning-on/off timing of each of the LEDs is appropriately shifted toadjust the positions of the respective light blocking portions. Asillustrated in FIG. 18( c), it is possible to form a desired lightdistribution pattern including a light blocking portion even though theplurality of LEDs are used. Further, the maximum light intensity, whichis hardly achieved by one LED, is achieved in the combined lightdistribution pattern.

Fifth Embodiment

FIG. 19 is a top view schematically showing the structure that includesan optical unit according to a fifth embodiment.

The optical unit 150 according to this embodiment includes a rotatingreflector 26 and a plurality of light sources that include LEDs as lightemitting elements. Among the plurality of light sources, one lightsource 152 includes a plurality of LED units 152 a, 152 b, and 152 c.The plurality of LED units 152 a, 152 b, and 152 c are LED units forconcentrating light, and are disposed so as to achieve the strongconcentration of light to the front in a traveling direction suitablefor a high beam-light distribution pattern. Among the plurality of lightsources, the other light source 154 includes a plurality of LED units154 a and 154 b. The plurality of LED units 154 a and 154 b are LEDunits for diffusing light, and are disposed so as to achieve diffusedlight that irradiates a wide range suitable for a high beam-lightdistribution pattern. Meanwhile, each of the light sources does not needto necessarily include a plurality of LED units, and may include one LEDunit as long as sufficient brightness can be achieved. Further, all LEDunits do not need to be always turned on, and only a part of the LEDunits may be turned on according to the traveling state of a vehicle orthe condition of a front region.

The light sources 152 and 154 are disposed so that the light emittedfrom the light sources 152 and 154 is reflected at different positionsby the respective blades of the rotating reflector 26. Specifically, theLED units 152 a, 152 b, and 152 c for concentrating light of the lightsource 152 are disposed so that the light emitted from the LED units 152a, 152 b, and 152 c is reflected by the fan-shaped blades 26 apositioned more distant from a first projection lens 156. For thisreason, a change in the position of the light source 152, which iscaused by the reflection of light using the fan-shaped blades 26 a, canbe projected forward by the first projection lens 156 of which the focallength is long (projection magnification is low). As a result, when afront region is scanned with the light emitted from the light source 152while the rotating reflector 26 is rotated, it is possible to form alight distribution pattern of which a scan range is not wide enough andwhich more brightly illuminates a narrow range.

Meanwhile, the LED units 154 a and 154 b for diffusing light of thelight source 154 are disposed so that the light emitted from the LEDunits 154 a and 154 b is reflected by the fan-shaped blades 26 apositioned more close to a second projection lens 158. For this reason,a change in the position of the light source 154, which is caused by thereflection of light using the fan-shaped blades 26 a, can be projectedby the second projection lens 158 of which the focal length is short(projection magnification is high). As a result, when a front region isscanned with the light emitted from the light source 154 while therotating reflector 26 is rotated, it is possible to form a lightdistribution pattern of which a scan range is wide and which illuminatesa wide range.

Since the plurality of light sources 152 and 154 are disposed asdescribed above so that the light emitted from the respective lightsources 152 and 154 is reflected at different positions on thereflecting surface of the rotating reflector 26, it is possible to forma plurality of light distribution patterns and to form new lightdistribution patterns by combining these light distribution patterns.Accordingly, it is easier to design an ideal light distribution pattern.

Next, the position of each of the projection lenses will be described.The light emitted from the light sources 152 and 154 enters therespective projection lenses by being reflected by the blades 26 a asdescribed above. This is equivalent to the fact that light beams enterthe respective projection lenses from secondary light sources of thelight sources 152 and 154 virtually formed on the back sides of theblades 26 a. When a light distribution pattern is formed by the scanningof light, it is important to project and scan a light source image,which is as clear as possible without being blurred, in order to improveresolution.

Accordingly, it is preferable that the focal point of the lenscorrespond to the secondary light source at the position of each of theprojection lenses. Meanwhile, considering required various irradiationpatterns and the fact that the positions of the secondary light sourcesof the light sources 152 and 154 are changed with the rotation of theblades 26 a, all the secondary light sources do not need to necessarilycorrespond to the focal points of the projection lenses.

On the basis of such knowledge, for example, the first projection lens156 is disposed so that at least one of the secondary light sources ofthe light source 152 formed by the reflection of light using the blades26 a passes through the vicinity of the focal point of the firstprojection lens 156. Further, the second projection lens 158 is disposedso that at least one of the secondary light sources of the light source154 formed by the reflection of light using the blades 26 a passesthrough the vicinity of the focal point of the second projection lens158.

FIG. 20 is a view schematically showing a light distribution patternthat is formed by a vehicle headlight including the optical unitaccording to the fifth embodiment. A high beam-light distributionpattern PH illustrated in FIG. 20 includes a first light distributionpattern PH1 that is formed by the light source 152 and brightlyirradiates a region in front of a vehicle in the distance, and a secondlight distribution pattern PH2 that is formed by the light source 154and irradiates a wide range in front of a vehicle.

Meanwhile, the optical unit 150 according to this embodiment furtherincludes the first projection lens 156 and the second projection lens158. The first projection lens 156 projects the light, which is emittedfrom the light source 152 and reflected by the rotating reflector 26, inthe light irradiation direction of the optical unit as the first lightdistribution pattern PH1. The second projection lens 158 projects thelight, which is emitted from the light source 154 and reflected by therotating reflector 26, in the light irradiation direction of the opticalunit as the second light distribution pattern PH2. Accordingly, it ispossible to form different light distribution patterns with one rotatingreflector by appropriately selecting each of the projection lenses.

Next, irradiation patterns, which are formed by the respective LEDsforming the first and second light distribution patterns PH1 and PH2,will be described. FIG. 21( a) is a view showing light distributionpatterns that are formed by the light sources 152 and 154, and FIGS. 21(b) to 21(f) are views showing irradiation patterns that are formed bythe respective LED units 152 a, 152 b, 152 c, 154 a, and 154 b. Asillustrated in FIGS. 21( b) to 21(d), the irradiation regions of theirradiation patterns formed by the LED units 152 a, 152 b, and 152 c aresmall and the maximum light intensities thereof are high. Meanwhile, asillustrated in FIGS. 21( e) and 21(f), the maximum light intensities ofthe irradiation patterns formed by the LED units 154 a and 154 b are lowbut the irradiation regions thereof are large. Further, when theirradiation patterns of the respective LEDs are superimposed, a highbeam-light distribution pattern illustrated in FIG. 21( a) is formed.

Next, the LED units of the light sources 152 and 154 will be describedin more detail. FIG. 22( a) is a perspective view of the LED unitaccording to the fifth embodiment, FIG. 22( b) is a cross-sectional viewtaken along line C-C of FIG. 22( a), and FIG. 22( c) is across-sectional view taken along line D-D of FIG. 22( a). The LED unit152 a of the light source 152 according to this embodiment includes LEDs160 and a compound parabolic concentrator 162 that concentrates thelight of the LEDs 160. Meanwhile, since the respective LED units 152 a,152 b, 152 c, 154 a, and 154 b have the same structure, the LED unit 152a will be described below by way of example.

The compound parabolic concentrator 162 is a member where the LEDs 160are disposed on the bottom and a rectangular opening portion 162 a isformed. The compound parabolic concentrator 162 includes four sidesurfaces (light concentrating surfaces) 162 b to 162 e that are formedfrom the bottom toward the opening portion 162 a in order to concentratethe light of the LEDs 160. The four side surfaces 162 b to 162 e aresubjected to mirror-finishing so as to have the shape of a parabola thathas a focal point on the LEDs 160 or in a region near the LEDs 160.Accordingly, the light emitted from the LEDs 160 is concentrated andemitted forward. Meanwhile, the light emitted from the LEDs 160 is aptto be diffused in the longitudinal direction of the opening portion 162a as denoted by arrows that are illustrated in FIG. 22( c) by a dottedline. For this reason, if all the side surfaces have the same height,there is a case that it is not possible to sufficiently concentrate thelight, which is directed in the longitudinal direction of the openingportion 162 a, of the light emitted from the LEDs 160. That is, a partof the light, which is obliquely emitted from the opening portion as itis without being reflected by the side surfaces, does not reach thereflecting surface of the rotating reflector 26.

Accordingly, in the compound parabolic concentrator 162 according tothis embodiment, the respective four side surfaces are formed so thatthe height H1 of each of the side surfaces 162 b and 162 c correspondingto the end portions of the opening portion 162 a in the longitudinaldirection of the opening portion 162 a is higher than the height H2 ofeach of the side surfaces 162 d and 162 e corresponding to the endportions of the opening portion 162 a in the width direction of theopening portion 162 a. Therefore, the generation of the diffused light,which does not reach the reflecting surface of the rotating reflector,of the light of the LEDs 160 is suppressed, so that the amount of lightentering the respective projection lenses is increased. As a result, itis possible to efficiently use the light of the light source forillumination.

Meanwhile, it is possible to form a light blocking portion at a lightdistribution pattern even though the optical unit 150 according to thisembodiment is used. FIG. 23( a) is a view showing a light distributionpattern that is formed by the light sources 152 and 154 and includes alight blocking portion, and FIGS. 23( b) to 23(f) are views showingirradiation patterns that are formed by the respective LED units 152 a,152 b, 152 c, 154 a, and 154 b and include light blocking portions. Asillustrated in FIGS. 23( b) to 23(d), the irradiation regions of theirradiation patterns, which are formed by the LED units 152 a, 152 b,and 152 c and include a light blocking portion, are small and themaximum light intensities thereof are high. Meanwhile, as illustrated inFIGS. 23( e) and 23(f), the maximum light intensities of the irradiationpatterns, which are formed by the LED units 154 a and 154 b and includelight blocking portions, are low but the irradiation regions thereof arelarge. Further, when the irradiation patterns of the respective LEDs aresuperimposed, a high beam-light distribution pattern, which isillustrated in FIG. 23( a) and includes a light blocking portion, isformed.

Sixth Embodiment

In the optical unit according to each of the above-mentionedembodiments, two irradiation beams simultaneously appear in differentdirections when light simultaneously enters both the adjacent blades.Accordingly, both end portions of a light distribution pattern shine atthe same time. In this case, it is difficult to independently controlthe irradiation states of both the end portions of the lightdistribution pattern. Accordingly, the light sources are turned off atthe timing where light simultaneously enters both the adjacent blades sothat both the end portions of the light distribution pattern are notsimultaneously irradiated. Meanwhile, if the light sources aretemporarily turned off at the above-mentioned timing, the brightness ofboth the end portions of the light distribution pattern is reduced tosome extent.

Accordingly, the rotating reflector according to this embodiment isprovided with partition members between the adjacent blades to suppressthe reduction of the brightness of a light distribution pattern. FIG. 24is a perspective view of a rotating reflector according to a sixthembodiment. A rotating reflector 164 illustrated in FIG. 24 includesthree blades 164 a that have the same shape as the blades of theabove-mentioned rotating reflector 26 and are arranged in thecircumferential direction of a cylindrical rotating part 164 b. Each ofthe blades 164 a functions as a reflecting surface. Further, therotating reflector 164 further includes three rectangular partitionmembers 164 c that are provided between the adjacent blades 164 a andextend in the direction of a rotation axis. The partition member 164 cis formed so as to suppress the incidence of light emitted from a lightsource upon the reflecting surface of the other adjacent blade when thelight emitted from the light source enters the reflecting surface of oneadjacent blade. Accordingly, it is possible to block the light, which isdirected toward the end portion of an adjacent blade, of the light,which is emitted from the light source and irradiates the end portion ofone blade, to some extent. That is, since the time, which passes whilelight simultaneously enters both the adjacent blades, is shortened, itis also possible to correspondingly shorten the time that passes whilethe light source is turned off. Accordingly, it is possible to suppressthe deterioration of irradiation efficiency to the minimum.

Next, appropriate numbers will be examined as the number of the bladesof the rotating reflector. The vehicle headlight including the opticalunit according to each of the above-mentioned embodiments irradiates anobject to be irradiated (for example, a vehicle or a pedestrian), whichis present in a front region, by reflecting the light of the lightsource and scanning the front region while the blades of the rotatingreflector are rotated. For this reason, the object to be irradiated isbrightened when irradiated with light and is darken when not irradiatedwith light. Accordingly, the object to be irradiated seems to beflickered according to conditions. A flicker frequency where an objectto be irradiated flickering in a stop state as described above is notperceived as flicker generally needs to be set to 80 Hz or more.

Further, a flicker frequency needs to be set to 300 Hz or more in orderto suppress a phenomenon (a so-called stroboscopic effect) where anobject to be irradiated, which is present in a front region, is seen ina granular shape due to the movement of the line of sight. Consideringflicker or a stroboscopic effect as described above, the entireirradiation pattern requires a scanning frequency of 300 Hz or more.However, if an irradiation pattern corresponds to only a very smallregion, a stroboscopic effect does not easily occur in the region duringthe travel of a vehicle. Accordingly, a scanning frequency in the smallregion may be 80 Hz or more.

The number of blades or the rotational speed of the rotating reflectormay be determined on the basis of such knowledge. Meanwhile, when allthe shapes of the plurality of blades are not the same, the shapes ofthe irradiation patterns scanned using the respective blades do notcompletely correspond to each other. FIG. 25( a) is a view showing anideal irradiation pattern when the shapes of the respective blades arecompletely the same, and FIG. 25( b) is a view showing an irradiationpattern when there is an error in the shape of each of the blades.Meanwhile, the irradiation patterns illustrated in FIG. 25 are formedwhen a rotating reflector including two blades is rotated at a speed of100 revolutions per second.

When the shapes of the respective blades are completely the same asillustrated in FIG. 25( a), the irradiation patterns scanned using allthe blades completely overlap each other. For this reason, when anobject to be irradiated is irradiated with the irradiation patterns, theobject to be irradiated flickers at 200 Hz. Meanwhile, when there is anerror in the shape of each of the blades as illustrated in FIG. 25( b),the central portions of the irradiation patterns overlap each other butthe outer peripheral portions of the irradiation patterns are shiftedfrom each other by the blades that perform scanning. For this reason,objects to be irradiated, which are present at the central portions ofthe irradiation patterns, flicker at 200 Hz, but objects to beirradiated, which are present in the vicinity of the outer peripheralportions of the irradiation patterns, flicker at 100 Hz that correspondsto the rotational speed of the rotating reflector. It is considered thata flicker frequency differs depending on an irradiation region of theirradiation pattern when there is an error in the shape of the blade asdescribed above.

In the central portion of the irradiation pattern that is significantlyaffected by a stroboscopic effect as described above, the rotationalspeed of the rotating reflector and the number of the blades may bedetermined so that the flicker frequency of an object to be irradiatedis 300 Hz or more. Meanwhile, since the outer peripheral portion of theirradiation pattern is a small region, a stroboscopic effect does noteasily occur. Accordingly, the rotational speed of the rotatingreflector and the number of the blades may be determined so that theflicker of an object to be irradiated, which flickers in a stop state,is not perceived and the flicker frequency of the object to beirradiated is 80 Hz or more.

For example, if the rotational speed of the rotating reflector is 150revolutions per second or more when the number of the blades of therotating reflector is two, a scanning frequency in the central portionof the irradiation pattern is 300 Hz or more and a scanning frequency inthe vicinity of the outer peripheral portion of the irradiation patternis 150 Hz or more. Likewise, if the rotational speed of the rotatingreflector is 100 revolutions per second or more when the number of theblades of the rotating reflector is three, a scanning frequency in thecentral portion of the irradiation pattern is 300 Hz or more and ascanning frequency in the vicinity of the outer peripheral portion ofthe irradiation pattern is 100 Hz or more. Further, if the rotationalspeed of the rotating reflector is 80 revolutions per second or morewhen the number of the blades of the rotating reflector is four, ascanning frequency in the central portion of the irradiation pattern is320 Hz or more and a scanning frequency in the vicinity of the outerperipheral portion of the irradiation pattern is 80 Hz or more.Furthermore, if the rotational speed of the rotating reflector is 80revolutions per second or more when the number of the blades of therotating reflector is five, a scanning frequency in the central portionof the irradiation pattern is 400 Hz or more and a scanning frequency inthe vicinity of the outer peripheral portion of the irradiation patternis 80 Hz or more. Moreover, if the rotational speed of the rotatingreflector is 80 revolutions per second or more when the number of theblades of the rotating reflector is six, a scanning frequency in thecentral portion of the irradiation pattern is 480 Hz or more and ascanning frequency in the vicinity of the outer peripheral portion ofthe irradiation pattern is 80 Hz or more.

When the rotational speed or the number of the blades of the rotatingreflector is appropriately selected in this way, the flicker of anobject to be irradiated, which is present in the irradiation pattern, orthe occurrence of a stroboscopic effect is suppressed. Meanwhile, it ispreferable that rotational speed be low in terms of the durability of adrive source (for example, a motor) that drives the rotating reflector.Meanwhile, the light source is turned off at the timing where theboundary portion of an adjacent blade is irradiated as described above.Accordingly, as the number of the blades is increased, turning-off timeis increased. For this reason, it is preferable that the number of theblades be small in terms of the efficient use of the light of the lightsource. Accordingly, the rotational speed of the rotating reflectoraccording to this embodiment may be equal to or higher than 80revolutions per second and lower than 150 revolutions per second.Further, it is preferable that the number of the blades be two, three,or four.

The rotating reflector including four blades will be described below.The blowing capacity of the optical unit is increased with the increaseof the number of the blades. FIG. 26 is a perspective view of a rotatingreflector according to a modification of the sixth embodiment. FIG. 27is a side view of the rotating reflector illustrated in FIG. 26.

A rotating reflector 166 illustrated in FIGS. 26 and 27 includes fourblades 166 a that are arranged in the circumferential direction of acylindrical rotating part 166 b. The blade 166 a has the shape of a fanhaving a central angle of 90°, and is twisted as in the above-mentionedrotating reflector. Each of the blades 166 a functions as a reflectingsurface. Further, the rotating reflector 166 further includes fourpartition plates 166 c that are provided between the adjacent blades 166a and extend in the direction of a rotation axis. The partition plate166 c is formed so as to suppress the incidence of light emitted from alight source upon the reflecting surface of the other adjacent bladewhen the light emitted from the light source enters the reflectingsurface of one adjacent blade. Accordingly, it is possible to block thelight, which is directed toward the end portion of an adjacent blade, ofthe light, which is emitted from the light source and irradiates the endportion of one blade, to some extent. That is, since the time, whichpasses while light simultaneously enters both the adjacent blades, isshortened, it is also possible to correspondingly shorten the time thatpasses while the light source is turned off. Accordingly, it is possibleto suppress the deterioration of irradiation efficiency to the minimum.Meanwhile, the partition plate 166 c includes two oblique sides 166 c 1and 166 c 2 that are formed at the upper portion thereof so as to beinclined with respect to the rotation axis.

FIG. 28 is a top view schematically showing the structure that includesthe optical unit according to the sixth embodiment. Meanwhile, the samestructures and members as those of the optical unit according to each ofthe above-mentioned embodiments will be denoted by the same referencenumerals and the description thereof will not be repeated.

An optical unit 170 according to this embodiment includes theabove-mentioned rotating reflector 166 and the plurality ofabove-mentioned light sources 152 and 154. The rotating reflector 166 isprovided with the partition plates 166 c between the adjacent blades 166a. The rotating reflector 166 is disposed so that a rotation axis R ofthe rotating reflector 166 of the optical unit 170 is inclined withrespect to an optical axis Ax of the optical unit 170.

The shape of the oblique side 166 c 1 of the partition plate 166 c isset so as to pass through the vicinity of the opening portions of therespective LED units 152 a, 152 b, and 152 c at the position facing thelight source 152. Further, the shape of the oblique side 166 c 1 is setso that the oblique side 166 c 1 is substantially parallel to thearrangement direction of the respective LED units 152 a, 152 b, and 152c when passing in front of the respective LED units 152 a, 152 b, and152 c. For this reason, the distances (gap G1) between the oblique side166 c 1 and the respective LED units become uniform when the obliqueside 166 c 1 passes in front of the respective LED units 152 a, 152 b,and 152 c. As a result, it is possible to align the turning-off timingof the respective LED units. Meanwhile, it is preferable that the gap G1be in the range of about 1 to 2 mm. Accordingly, when the light emittedfrom the light source enters the reflecting surface of one adjacentblade, the incidence of light emitted from a light source upon thereflecting surface of the other adjacent blade is prevented untilimmediately before the light source passes immediately above thepartition plates.

Meanwhile, the shape of the oblique side 166 c 2 of the partition plate166 c is set so as to pass through the vicinity of the opening portionsof the respective LED units 154 a and 154 b at the position facing thelight source 154. Further, the shape of the oblique side 166 c 2 is setso that the oblique side 166 c 2 is substantially parallel to thearrangement direction of the respective LED units 154 a and 154 b whenpassing in front of the respective LED units 154 a and 154 b. For thisreason, the distances (gap G2) between the oblique side 166 c 2 and therespective LED units become uniform when the oblique side 166 c 2 passesin front of the respective LED units 154 a and 154 b. As a result, it ispossible to align the turning-off timing of the respective LED units.Meanwhile, it is preferable that the gap G2 be in the range of about 1to 2 mm. Accordingly, when the light emitted from the light sourceenters the reflecting surface of one adjacent blade, the incidence oflight emitted from a light source upon the reflecting surface of theother adjacent blade is prevented until immediately before the lightsource passes immediately above the partition plates.

Since it is possible to suppress the incidence of light, by thepartition plate 166 c, emitted from the light source upon the reflectingsurface of the other adjacent blade when the light emitted from thelight source enters the reflecting surface of one adjacent blade asdescribed above, it is possible to shorten the turning-off time of thelight source. As a result, it is possible to suppress the deteriorationof the irradiation efficiency of the optical unit to the minimum.

Seventh Embodiment

A vehicle monitor according to a seventh embodiment includes an opticalunit and a camera. The optical unit forms a light distribution patternin front of a vehicle using the persistence of vision of the human eyeby scanning an irradiation beam in the left and right direction (or theup and down direction) with a rotating reflector, a resonance mirror, orthe like. The camera takes an image of a region in front of the vehicle.Since the imaging time of a general camera is milliseconds orsub-milliseconds, a state where a partial region of a light distributionpattern is irradiated with an irradiation beam is recorded in an imagetaken by the camera.

When a reflective object, such as a delineator or a signboard, whichreflects light, is irradiated with an irradiation beam, the reflectiveobject is imaged as a bright spot. However, when a reflective object ispresent at a position different from the position of an irradiationbeam, the reflective object is not imaged as a bright spot. Accordingly,it is possible to identify a bright spot, of which the light intensityis not significantly changed, as a self-luminous object such as a streetlight or a lamp of a vehicle-in-front and to identify a bright spot, ofwhich the light intensity is significantly changed, as a reflectiveobject, by setting scanning speed and the imaging timing of the cameraso that the irradiation position of an irradiation beam varies at everyimaging timing and analyzing continuous or a plurality of taken images.In addition, it is possible to identify a moving object such as avehicle lamp and a fixed object such as a street light, by usinginformation, such as light intensity or a distance, a color, an angle, amoving direction, and a positional relationship with the shapes of lineson the road.

FIG. 30 is a block diagram of a vehicle monitor according to a seventhembodiment. A vehicle headlight 10 illustrated in FIG. 30 includes alamp unit 20 that includes a rotating reflector 26 and a LED 28, a motor1034 that rotationally drives the rotating reflector 26, and a controlunit 1036 that controls the LED 28 and the motor 1034.

The control unit 1036 is provided with a CPU 1038, a ROM 1040, a RAM1042, a motor controller 1044 that controls the motor 1034 rotationallydriving the rotating reflector 26, and a light source controller 1046that controls the LED 28. A plurality of light distribution controlprograms is stored in the ROM 1040. The CPU 1038 selectively executesthese programs, outputs operation commands to the motor controller 1044and the light source controller 1046, and controls a light distributionpattern formed in front of a vehicle. Further, the control unit 1036 isconnected to an image processing device 1048 of the vehicle. The imageprocessing device 1048 analyzes the imaging data of an in-vehicle camera1050 and provides the information on the road surface in front of thevehicle to the control unit 1036.

The vehicle monitor according to this embodiment includes the lamp unit20 that forms a light distribution pattern by scanning an irradiationbeam to the front of the vehicle, the in-vehicle camera 1050 that takesan image of a region in front of the vehicle, and a determining devicethat determines whether a reflective body is present in front of thevehicle. Further, the determining device according to this embodiment isformed of the CPU 1038 and the image processing device 1048. On thebasis of an image that is taken by the in-vehicle camera 1050 when apartial region included in the light distribution pattern is irradiatedwith an irradiation beam and an image that is taken by the in-vehiclecamera 1050 when the partial region is not irradiated with anirradiation beam, the determining device determines whether a reflectivebody reflecting an irradiation beam is present in the partial region.

FIG. 31 is a view schematically showing a state where a partial region(a middle region in front of a vehicle) included in a light distributionpattern is irradiated with an irradiation beam. FIG. 32 is a viewschematically showing a state where a partial region (the middle regionin front of the vehicle) included in a light distribution pattern is notirradiated with an irradiation beam. In FIG. 31, a low beam-lightdistribution pattern PL and a high beam-light distribution pattern PH,which are formed on a virtual vertical screen disposed at a position 25m ahead of the vehicle by the light emitted from the vehicle headlight10, are superimposed on a view that perspectively shows a region infront of a subject vehicle when the vehicle travels on a paved straightroad having one lane on one side (having two lanes on both sides).Further, a centerline CL, a travel lane-side line MRL, and an oppositelane-side line ORL are illustrated in FIG. 31. The travel lane-side lineMRL extends toward the left lower side from an H-V point (anintersection between a horizontal line H-H and a vertical line V-V) thatis a vanishing point of a perspective view, and the centerline CL andthe opposite lane-side line ORL extends toward the right lower side fromthe H-V point. Meanwhile, a plurality of delineators 600 a to 600 f,which are provided on the left and right shoulders of the road, areillustrated in FIGS. 31 and 32.

The low beam-light distribution pattern PL is formed by an irradiationbeam emitted from the lamp unit 18 for a low beam. The low beam-lightdistribution pattern PL illustrated in FIG. 31 is a light distributionpattern that is considered so as not to direct glare at oncomingvehicles or pedestrians when a vehicle travels in an urban area or thelike in a region where vehicles and pedestrians keep to the leftaccording to a traffic regulation. The low beam-light distributionpattern PL includes cut-off lines CL1, CL2, and CL3, which havedifferent levels on the left and right, at the upper end edge thereof.The cut-off line CL1 is formed on the right side of the line V-V of thevehicle headlight 10 as a cut-off line corresponding to the oppositelane so as to extend in the horizontal direction. The cut-off line CL2is formed on the left side of the line V-V as a cut-off linecorresponding to the travel lane so as to extend in the horizontaldirection at a position higher than the cut-off line CL1. Further, thecut-off line CL3 is formed as an oblique cut-off line connecting an endportion of the cut-off line CL2, which is close to the line V-V, with anend portion of the cut-off line CL1 that is close to the line V-V. Thecut-off line CL3 obliquely extends toward the left upper side at anangle of inclination of 45° from a point of intersection of the cut-offline CL1 and the line V-V.

The high beam-light distribution pattern PH is formed by an irradiationbeam emitted from the lamp unit 20 for a high beam. The high beam-lightdistribution pattern PH is additionally formed on the low beam-lightdistribution pattern PL.

As illustrated in FIG. 31, a light distribution region of the highbeam-light distribution pattern PH has a substantially rectangular shapethat has long sides in the horizontal direction. Meanwhile, the highbeam-light distribution pattern PH is formed by scanning an irradiationbeam as described above. For this reason, when an image of a region infront of the vehicle is taken at the timing where an irradiation beamscans the middle region in front of the vehicle, an image, where aregion Ia corresponding to the projection image of the light source isbright since the region Ia is irradiated with an irradiation beam andregions Ib and Ic formed on both sides of the region Ia are dark, isobtained. According to the analysis of this image, in the middle regionin front of the vehicle that is a partial region included in the lightdistribution pattern, light reflected by the delineators 600 c and 600 dand a tail lamp TL of a vehicle-in-front 1052 are detected as brightspots.

Next, when an image of a region in front of the vehicle is taken at thetiming different from the imaging timing illustrated in FIG. 31 (seeFIG. 32), an image, where a region Ia′ corresponding to the projectionimage of the light source moved to the right side of the middle regionin front of the vehicle is bright since the region Ia′ is irradiatedwith an irradiation beam and regions Ib′ and Ic′ formed on both sides ofthe region Ia′ are dark, is obtained. According to the analysis of thisimage, in the middle region in front of the vehicle included in theregion Ib′, the tail lamp TL of the vehicle-in-front 1052 is detected asa bright spot but the delineators 600 c and 600 d are not detected asbright spots since the delineators 600 c and 600 d are not irradiatedwith an irradiation beam.

In this way, depending on whether the delineators are irradiated with anirradiation beam, it is determined whether the delineators appear asbright spots in the image. Then, processing for discriminating areflective body, such as a delineator or a sign, from a lamp of avehicle-in-front will be described using these properties.

FIG. 33 is a flowchart illustrating the processing for determining areflective body according to this embodiment. When forward irradiationusing a high beam-light distribution pattern is required according tothe driver's selection or the situation of travel environment, thescanning of a region in front of a vehicle with an irradiation beamemitted from the vehicle headlight 10 is started (S10). Next, the imageprocessing device 1048 acquires the data of the image of the region infront of the vehicle that is taken by the in-vehicle camera 1050 (S12),processes the image (S14), and sends the processed image to the CPU1038. The CPU 1038 extracts bright spots on the basis of the image dataof which the image has been processed (S16). The CPU 1038 extractsbright spots even on the basis of the data of a plurality of images thatare taken at different timings, and compares the plurality of images(S18).

Meanwhile, an image, which is taken when a region to which a driver paysattention (a middle region in front of the vehicle in this embodiment)is irradiated with an irradiation beam, and an image, which is takenwhen the region is not irradiated, are included in the plurality ofimages. Not only the tail lamp TL of the vehicle-in-front 1052 presenton the front but also the delineators 600 c and 600 d reflecting anirradiation beam can be detected from the image that is taken by thecamera when the middle region in front of the vehicle, which is includedin a light distribution pattern, is irradiated with an irradiation beam.Meanwhile, the tail lamp TL of the vehicle-in-front 1052 present on thefront can be detected from the image that is taken by the camera whenthe middle region in front of the vehicle is not irradiated with anirradiation beam, but the delineators 600 c and 600 d not irradiatedwith an irradiation beam are not detected.

Accordingly, whether a reflective body or a self-luminous object ispresent in a partial region is determined through the comparison betweenthe image that is taken when the partial region is irradiated with anirradiation beam and the image that is taken when the partial region isnot irradiated with an irradiation beam.

The CPU 1038 discriminates whether a reflective body is present in thepartial region on the basis of the analysis results of the plurality ofabove-mentioned images (S20). Specifically, if a bright spot, which isdetected at a position corresponding to the partial region in the imagetaken when the partial region is irradiated with an irradiation beam, isdetected as a vanishing point or a very dark point in the image that istaken when the partial region is not irradiated with an irradiationbeam, it is determined that the bright spot is a reflective body (Yes inS20). Since there is no concern that glare is directed even though theforward irradiation using a high beam-light distribution patterncontinues to be performed in this case, processing is temporarily ended.Meanwhile, if a bright spot is detected at a position corresponding tothe partial region in the image that is taken when the partial region isnot irradiated with an irradiation beam, it is determined that aself-luminous object is present in the partial region (No in S20).

The self-luminous object includes a street light, an illumination lamp,and the like other than a tail lamp TL or a headlamp HL of avehicle-in-front. Accordingly, the CPU 1038 determines whether theself-luminous object is a vehicle-in-front (S22). The determination ofwhether the self-luminous object is a vehicle-in-front is performedusing information, such as light intensity or a distance of the brightspot, a color, an angle, and a moving direction, and the relative speedof the self-luminous object, and the positional relationship between theself-luminous object and the shapes of lines on the road. If it isdetermined that the self-luminous object is not a vehicle-in-front (Noin S22), processing is temporarily ended since there is no concern thatglare is directed even though the forward irradiation using a highbeam-light distribution pattern continues to be performed. Meanwhile, ifit is determined that the self-luminous object is a vehicle-in-front(Yes in S22), glare is directed at the vehicle-in-front when the forwardirradiation using a high beam-light distribution pattern continues to beperformed. Accordingly, a control for blocking light in a regionincluding the vehicle-in-front is performed (S24).

The vehicle monitor according to this embodiment can discriminate areflective body present on the front while forming a normal highbeam-light distribution pattern as described above. For this reason,special control of light distribution does not need to be performed todetect a vehicle on the front, so that a driver does not feeldiscomfort. Further, since the vehicle monitor according to thisembodiment can suppress the erroneous detection of a reflective bodyincluding a delineator, the vehicle monitor can accurately and easilydetect a vehicle that travels on the front at night.

As described in each of the above-mentioned embodiments, the vehicleheadlight 10 is adapted to be capable of blocking light on apart of ahigh beam-light distribution pattern by turning on and off the LED 28.FIG. 34 is a view illustrating a state where light is blocked on a partof a high beam-light distribution pattern.

As illustrated in FIG. 34, a high beam-light distribution pattern PHincludes a light blocking portion Z and regions Ib″ and Ic″ formed onboth sides of the light blocking portion Z. According to the vehicleheadlight 10 of this embodiment, the control of light distribution usinga high beam-light distribution pattern can be performed in a range whereglare is not directed at a vehicle-in-front. Accordingly, forwardvisibility can be improved.

Next, imaging timing and the irradiation position of an irradiation beamthat is scanned horizontally will be described. FIG. 35 is a viewschematically illustrating an irradiation position and imaging timing.The optical unit according to the embodiment scans an irradiation beamso that a region irradiated with an irradiation beam varies at each ofthe timing of plural times of imaging that are performed by a camera.That is, the optical unit scans an irradiation beam so that a regionirradiated with an irradiation beam at the timing of Nth (here, N is anatural number) imaging performed by the in-vehicle camera 1050 isdifferent from a region irradiated with an irradiation beam at thetiming of (N+1)th imaging performed by the in-vehicle camera 1050.Meanwhile, an image to be taken may not necessarily be a continuousimage. Further, image data, which is obtained by averaging image data ofabout 3 to 10 frames, may be treated as one image.

If imaging timing and the irradiation position of an irradiation beamthat is scanned horizontally are shown while a horizontal axis is usedas a time axis as illustrated in FIG. 35, the shift amount “E” ofimaging timing relative to a scanning period is a remainder that isobtained when the number of times of scanning per second is divided bythe number of times of imaging. Meanwhile, FIG. 35 shows a case wherethe number of times of scanning is 7 times per second and the number oftimes of imaging is 3 times per second. In this case, the shift amount Eof imaging timing relative to a scanning period is ⅓ that is a remainderobtained when 7 is divided by 3.

FIG. 36 is a view schematically illustrating a condition where the sameregion of a continuous taken image is not continuously irradiated.

When the irradiation position of an irradiation beam in a previous takenimage is assumed as a left end of a scanned region (a zero position ofFIG. 36) as illustrated in FIG. 36, the same region of a continuoustaken image is not irradiated if the irradiation position at the nextimaging timing is in the range of F of FIG. 36.

Accordingly, assuming that the number of times of scanning of theoptical unit is represented by A [times/s], scanning speed isrepresented by B [deg/s], the width of an irradiation beam isrepresented by C [deg], and the number of times of imaging of the camerais represented by D [times/s], the irradiation range of an irradiationbeam in the latest taken image does not correspond to the irradiationrange of an irradiation beam in a taken image immediately before thelatest taken image when the following expression (1) is satisfied.

C≦(decimal part of A/D)×(B/A)≦(B/A)−C  Expression (1)

Here, it is preferable that the number A of times of scanning be in therange of about 60 to 1000 [times/s]. Further, it is preferable thatscanning speed B be in the range of about 10 to 60 [deg/s]. Furthermore,it is preferable that the width C of an irradiation beam be in the rangeof about 1 to 5 [deg]. Moreover, it is preferable that the number D oftimes of imaging of the camera be in the range of about 10 to 60[times/s]. Accordingly, it is possible to take an image when a certainregion is irradiated with an irradiation beam and an image when thecertain region is not irradiated with an irradiation beam.

Meanwhile, for example, the following expression (2) may be satisfied asa condition where the same positions in M taken images do not continueto be irradiated.

C/(N−1)≦(decimal part of A/D)×(B/A)≦(B/A)−C(N−1)  Expression (2)

Eighth Embodiment

The rotating reflector has been described as an optical unit by way ofexample in each of the above-mentioned embodiments, but a resonancemirror may be used. This embodiment will be described below withreference to the drawings. FIG. 37 is a schematic view showing theentire structure of a vehicle headlight according to an eighthembodiment. FIG. 38 is a perspective view showing a mirror unit and alight source unit. FIG. 39 is a view schematically showing thecombination of a light source, an optical system for shaping, and amirror. Meanwhile, the same structures as those of the above-mentionedembodiments are denoted by the same reference numerals and thedescription thereof will not be repeated.

As illustrated in FIG. 37, a vehicle headlight 110 according to theeighth embodiment includes a housing 1060 that is provided at the frontportion of a vehicle body. The front surface of the housing 1060 iscovered with a translucent cover 1062, and a mirror unit 1064 isinstalled at the central portion of the housing 1060. A base 1066 of themirror unit 1064 is mounted on the housing 1060 by a bracket 1068 so asto be inclined, and an extension 1070 is disposed between the base 1066and the translucent cover 1062. A light source unit 1072 and a controlunit 1036 are installed on the bottom wall of the housing 1060 below themirror unit 1064. A portion where the light source unit 1072 isinstalled is not limited to an example illustrated in FIG. 37, and maybe a side wall of the housing 1060.

The control unit 1036 is provided with a CPU 1038, a ROM 1040, a RAM1042, an actuator controller 1076 that controls a scanning actuator 1074(see FIG. 38) of the mirror unit 1064, and a light source controller1046 that controls a light source 1078 of the light source unit 1072. Aplurality of light distribution control programs is stored in the ROM1040. The CPU 1038 selectively executes these programs, outputsoperation commands to the actuator controller 1076 and the light sourcecontroller 1046, and controls a light distribution pattern formed infront of a vehicle. Further, the control unit 1036 is connected to animage processing device 1048 of the vehicle. The image processing device1048 analyzes the imaging data of an in-vehicle camera 1050 and providesthe information on the road surface in front of the vehicle to thecontrol unit 1036.

As illustrated in FIG. 38, the base 1066 of the mirror unit 1064 isprovided with a turning body 1082 in an opening portion 1080 and amirror 1084 is formed on the surface of the turning body 1082 by meansof such as plating or deposition. The turning body 1082 is supported bya vertical torsion bar 1086 so that the turning body 1082 can be turnedto the left and right relative to the base 1066. Permanent magnets 1088,which form magnetic fields orthogonal to the torsion bar 1086, aredisposed on the left and right sides of the base 1066. A coil 1090 iswired in the turning body 1082, and is connected to the control unit1036 through a terminal part 1092. Further, the permanent magnets 1088and the coil 1090 form the scanning actuator 1074. The actuatorcontroller 1076 controls the intensity and direction of drive currentflowing in the coil 1090, so that the turning body 1082 isreciprocatively turned integrally with the mirror 1084 about a verticalaxis (O).

The light source unit 1072 is provided with the light source 1078 at thelower portion of a casing 1094 (see FIG. 37), and is provided with aplano-convex lens 1096 as the optical system for shaping at the upperportion of the casing 1094. The light source 1078 is formed of aplurality of light emitting elements 1098, the light emitting elements1098 are arranged on a light source substrate 1100, and a heat sink 1102for cooling the light emitting elements 1098 is provided on the lowersurface of the light source substrate 1100. A LED, which emits diffusedlight DR, is used as the light emitting element 1098, and a plurality ofLEDs are arranged on the light source substrate 1100 in a predeterminedform. Further, the plano-convex lens 1096 shapes the light emitted fromthe light source 1078 so that the light emitted from the light source1078 corresponds to the size of the mirror 1084, and makes the lightenter the mirror 1084. Accordingly, it is possible to make the light,which is reflected by the mirror 1084, bright by the effective use ofthe light of the plurality of light emitting elements 1098.

Since the plano-convex lens 1096 is used as the optical system forshaping in the vehicle headlight 110 according to this embodiment, asillustrated in FIG. 39, the light emitted from the light source 1078(the diffused light DR of the LEDs) enters the mirror 1084 as parallellight PR after being shaped by the plano-convex lens 1096. For thisreason, the mirror 1084 can reflect the parallel light as it is, and candirectly scan reflected light RP to the front of the vehicle.Accordingly, an optical system for concentrating light such as aprojection lens may be omitted from the front of the mirror 1084, sothat it is possible to reduce the number of parts of the optical systemof the vehicle headlight 110. Further, there is also an advantage thatthe mirror 1084 can be turned at a large angle and widely scan a regionin front of the vehicle without a limitation by the optical system forconcentrating light.

Ninth Embodiment

The vehicle monitor using one rotating reflector, which is provided inone of left and right vehicle headlights 10, has been described in theseventh embodiment, but the invention is not necessarily limited to thiscombination. A vehicle monitor using a plurality of rotating reflectors26, which are provided in lamp units 20 of the respective left and rightvehicle headlights 10, will be described in this embodiment. Meanwhile,in this embodiment, the same structure as that of each of theabove-mentioned embodiments will be denoted by the same referencenumerals and the description thereof will not be repeated.

A general vehicle includes a pair of left and right vehicle headlights10. Accordingly, a case where the images of light distribution patternsformed by irradiation beams of two optical units of the left and rightvehicle headlights 10 are taken will be described in this embodiment.

A vehicle monitor according to this embodiment includes two lamp units20 that form a light distribution pattern by scanning irradiation beamsto the front of the vehicle, an in-vehicle camera 1050 that takes animage of a region in front of the vehicle, and a determining device thatdetermines whether a reflective body is present in front of the vehicle.The two lamp units 20 are built in the above-mentioned vehicleheadlights 10, which are provided at the left and right portions of thevehicle, respectively. Further, the determining device according to thisembodiment is formed of a CPU 1038 and an image processing device 1048.On the basis of an image that is taken by the in-vehicle camera 1050when a partial region included in the light distribution pattern isirradiated with irradiation beams and an image that is taken by thein-vehicle camera 1050 when the partial region is not irradiated withirradiation beams, the determining device determines whether areflective body reflecting irradiation beams is present in the partialregion.

FIG. 40 is a view schematically showing a state where a partial regionincluded in a light distribution pattern is irradiated with twoirradiation beams. In FIG. 40, at certain timing, an irradiation regionof a first optical unit of the right vehicle headlight 10 is representedby S1 and an irradiation region of a second optical unit of the leftvehicle headlight 10 is represented by S2. The vehicle monitor accordingto this embodiment drives the respective optical units (rotatingreflectors 26) so that an irradiation region of the light distributionpattern is changed at the timings of a plurality of times of imagingperformed by the in-vehicle camera 1050. In other words, the vehiclemonitor according to this embodiment drives the rotating reflectors 26so that irradiation regions of the light distribution pattern do notcorrespond to each other at the respective timings of the imagingperformed by the in-vehicle camera 1050.

Two cases to be described below are considered as a condition whereirradiation regions of the irradiation beams forming a lightdistribution pattern are not changed at the respective imaging timings.First, Case 1 illustrated in FIG. 40 is a case where the irradiationregions of the irradiation beams of the respective two rotatingreflectors 26 are not changed at the respective imaging timings. Thatis, in Case 1 illustrated in FIG. 40, the position of S1 that is anirradiation region of a first rotating reflector of the right vehicleheadlight 10 and the position of S2 that is an irradiation region of asecond rotating reflector of the left vehicle headlight 10 are notchanged at the respective imaging timings (first to fourth frames).

This condition corresponds to a case where the scanning frequency ofeach of the rotating reflectors is the integer multiple of the imagingfrequency of the camera. In more detail, assuming that the number oftimes of scanning (scanning frequency) of the first rotating reflectoris represented by A1 (times/s), the number of times of scanning(scanning frequency) of the second rotating reflector is represented byA2 (times/s), the number of times of imaging (imaging frequency) of thein-vehicle camera 1050 is represented by D (times/s), and m and n arenatural numbers, this condition corresponds to a case where equationsmD=A1 and nD=A2 are satisfied.

Next, Case 2 illustrated in FIG. 40 is a case where the irradiationregions of the irradiation beams of the respective rotating reflectorsare changed at every imaging timing but an irradiation region (S1+S2)where the irradiation beams of the two rotating reflectors are combinedis not changed apparently. That is, in Case 2 illustrated in FIG. 40, anirradiation region of an irradiation beam of the first rotatingreflector is S1 and an irradiation region of an irradiation beam of thesecond rotating reflector is S2 in the first frame (third frame) that isimaged by the in-vehicle camera 1050. Further, an irradiation region S1′of an irradiation beam of the first rotating reflector in the secondframe (fourth frame), which is imaged by the in-vehicle camera 1050, isthe same as the irradiation region S2 of the irradiation beam of thesecond rotating reflector in the first frame (third frame) that isimaged by the in-vehicle camera 1050. Likewise, an irradiation regionS2′ of an irradiation beam of the second rotating reflector in thesecond frame (fourth frame), which is imaged by the in-vehicle camera1050, is the same as the irradiation region S1 of the irradiation beamof the first rotating reflector in the first frame (third frame) that isimaged by the in-vehicle camera 1050. Accordingly, in Case 2, theirradiation region (S1+S2) where the irradiation beams of the tworotating reflectors are combined is not changed apparently at therespective imaging timings (first to fourth frames).

This condition corresponds to a case where the scanning frequency ofeach of the rotating reflectors is the (integer+0.5) multiple of theimaging frequency of the camera and the phases of irradiation beams ofthe respective rotating reflectors are shifted from each other by a halfperiod. In more detail, assuming that the number of times of scanning(scanning frequency) of the first rotating reflector is represented byA1 (times/s), the number of times of scanning (scanning frequency) ofthe second rotating reflector is represented by A2 (times/s), the numberof times of imaging (imaging frequency) of the in-vehicle camera 1050 isrepresented by D (times/s), and m and n are natural numbers, thiscondition corresponds to a case where equations (m+0.5)D=A1 and(n+0.5)D=A2 are satisfied.

The vehicle monitor according to this embodiment needs to rotationallydrive the respective rotating reflectors so that the scanning using theirradiation beams of the respective rotating reflectors does not satisfythe condition of Case 1 or 2. That is, assuming that the number of timesof scanning of the first optical unit is represented by A1 (times/s),the number of times of scanning of the second optical unit isrepresented by A2 (times/s), the number of times of imaging of thein-vehicle camera 1050 is represented by D (times/s), and m and n arenatural numbers, the vehicle monitor controls the rotating reflectors soas to satisfy the following expressions (1) and (2).

mD<A1<(m+0.5)D or (m+0.5)D<A1<(m+1)D  Expression (1)

nD<A2<(n+0.5)D or (n+0.5)D<A2<(n+1)D  Expression (2)

Meanwhile, if the number A1 of times of scanning and the number A2 oftimes of scanning are too close to the integer multiple or [integer+0.5]multiple of the number D of times of imaging, the movement of anirradiation region at every imaging timing is reduced. For this reason,time, which is required to ordinarily take an image of the entire regionof the light distribution pattern having been irradiated, is lengthened.Accordingly, there is also considered a case where the furtherimprovement of the responsiveness or detection accuracy of the vehiclemonitor is required. In this case, it is preferable that the number A1of times of scanning and the number A2 of times of scanning be a valuedifferent from the integer multiple or [integer+0.5] multiple of thenumber D of times of imaging to some extent.

Accordingly, as a result of earnest examination, the present inventorhas found that it is preferable that the vehicle monitor control therotating reflectors so as to satisfy the following expressions (3) and(4).

(m+0.1)D<A1<(m+0.4)D or (m+0.6)D<A1<(m+0.9)D  Expression (3)

(n+0.1)D<A2<(n+0.4)D or (n+0.6)D<A2<(n+0.9)D  Expression (4)

The vehicle monitor according to this embodiment can improveresponsiveness or detection accuracy by controlling the rotation of therotating reflectors 26 or imaging timing so that Expressions (3) and (4)are satisfied.

Meanwhile, the above-mentioned DC brushless motor may be used to drivethe rotating reflectors of the vehicle monitor according to thisembodiment. The DC brushless motor can output rotation timinginformation. For this reason, for example, the above-mentioned controlunit 1036 can control not only the rotational speed of the motor 1034but also the rotational speed of the rotating reflector 26 bycalculating rotational speed on the basis of information about thedetected rotation timing and adjusting an output signal (output voltage)of the motor controller 1044.

Accordingly, since the vehicle monitor is provided with this controlunit 1036, the vehicle monitor can easily change the rotational speed ofthe rotating reflector 26 to an appropriate value considering theimaging timing of the in-vehicle camera 1050.

Tenth Embodiment

In the past, generally, a radar using invisible light such as millimeterwaves has included a plurality of receiving antennas, and has detectedthe direction or distance of an obstruction using obtained receivedsignals by sequentially selecting the receiving antennas throughswitches or digital signal processing. However, since there is arestriction in reducing the size of the invisible-light radar thatincludes the plurality of receiving antennas, a place where the radar isinstalled is limited.

As a result of the recognition and earnest examination of this problem,the present inventor has thought up the structure of a certainobstruction detector. This obstruction detector can scan the surroundingregion and detect an obstruction by reflecting invisible light, which issent from an invisible-light radar, with a rotating reflector. In thiscase, if the waveform of a received signal and a region scanned at thetiming where the received signal has been detected are known even thougha plurality of receiving antennas are not provided, it is also possibleto calculate the direction, the distance, or the like of an obstruction.

The invisible-light radar may use electromagnetic waves of variouswavelength bands. However, a millimeter-wave radar using millimeterwaves will be described below by way of example. Meanwhile, since thereare various standards of wavelengths of millimeter waves according tocountries or uses, wavelengths of millimeter waves are not particularlylimited. For example, millimeter waves corresponding to, for example, a47 GHz band (46.7 to 46.9 GHz), a 60 GHz band (59 to 66 GHz or 63 to 64GHz), a 76 GHz band (76 to 77 GHz), a 94 GHz band (94.7 to 95.7 GHz), a139 GHz band (139 to 140 GHz), and the like may be used.

Meanwhile, an obstruction detector according to this embodiment may alsohave a function as an optical unit of a vehicle lamp. That is, theobstruction detector may be formed using the optical unit of each of theabove-mentioned embodiments. FIG. 41 is a top view schematically showingan obstruction detector according to a tenth embodiment. An obstructiondetector 2100 according to this embodiment includes a millimeter-waveradar 2102, a rotating reflector 26 that is rotated about a rotationaxis R in one direction while reflecting millimeter waves sent from themillimeter-wave radar 2102, and a projection lens 130 that focuses themillimeter waves reflected by the rotating reflector 26 and projects themillimeter waves to a surrounding region. The rotating reflector 26 isprovided with a reflecting surface so as to scan the surrounding regionwith the millimeter waves that are reflected by the rotating reflector26 while the rotating reflector 26 is rotated.

The millimeter-wave radar 2102 includes a monolithic millimeter-waveintegrated circuit (MMIC: hereinafter, referred to as a “millimeter-waveintegrated circuit”) 2104 for a millimeter-wave radar, and a waveguide2106 that is connected to the millimeter-wave integrated circuit 2104.The millimeter-wave integrated circuit 2104 sends predeterminedmillimeter waves of which the wavelengths are in the range of 1 to 10millimeters and the frequencies are in the range of 30 to 300 GHz. Thewaveguide 2106 is provided so as to pass through the central portion ofa heat sink 2108 on which LEDs 28 a and 28 b as light sources aremounted. That is, the millimeter-wave radar 2102 and the light sourcesare unitized in this embodiment. Further, the waveguide 2106 functionsas both a sending part and a receiving part.

The sent millimeter waves are directed to the rotating reflector 26through the waveguide 2106, and are reflected by blades 26 a. The blades26 a have a twisted shape so that an angle between an optical axis andthe reflecting surface is changed in the circumferential directionhaving a center on the rotation axis R. For this reason, the directionsof the millimeter waves reflected by the blades 26 a are changed by therotation of the rotating reflector 26 so that the millimeter wavesreflected by the blades 26 a are directed to the projection lens 130.The millimeter waves entering the projection lens 130 are refracted andfocused, so that the directivity of the millimeter waves is improved.The focused millimeter waves scan a region in front of the projectionlens 130 in the state of irradiation beams.

Accordingly, since the obstruction detector 2100 according to thisembodiment can scan the surrounding region with millimeter waves by theoperation of the rotating reflector 26, it is possible to simplify thestructure of the millimeter-wave radar 2102. Further, the diameter ofthe rotating reflector 26 according to this embodiment is substantiallythe same as the diameter of the projection lens 130 and the area of theblade 26 a can also be increased according to the diameter of therotating reflector 26. Accordingly, it is possible to efficientlyreflect millimeter waves of which the directivity is low and whichspread.

Furthermore, an in-vehicle millimeter-wave radar in the related art hasoften been disposed near a front grille, which is formed at the frontportion of a vehicle, to sufficiently exhibit the performance thereof.However, the obstruction detector 2100 according to this embodimentreflects the millimeter waves, which are sent from the millimeter-waveradar 2102, by the rotating reflector 26, and scans the surroundingregion with the reflected millimeter waves through the projection lens130. In this case, the projection lens 130 apparently functions as anantenna of the radar. For this reason, the millimeter-wave radar 2102does not need to be disposed on the outermost portion of the obstructiondetector, and the emission direction of millimeter waves of themillimeter-wave radar 2102 also does not need to be directly directed toa scan range. For this reason, not only the degree of freedom of a placewhere the millimeter-wave radar 2102 is disposed can be increased andbut also the obstruction detector can be disposed in a suitable place.Here, the surrounding region is a region around a place where theobstruction detector 2100 is installed. When the obstruction detector2100 is installed in a vehicle as in this embodiment, the front, therear, the side, and the like of the vehicle are included in thesurrounding region.

The obstruction detector 2100 according to this embodiment furtherincludes LEDs 28 a and 28 b that are semiconductor light emittingelements. As described in the above-mentioned embodiments, the rotatingreflector 26 is provided with a reflecting surface so as to form adesired light distribution pattern in front of the vehicle by reflectingthe light emitted from the LEDs 28 a and 28 b while being rotated.Further, the projection lens 130 projects the light, which is reflectedby the rotating reflector 26, in the light irradiation direction.Accordingly, it is possible to achieve the scanning using millimeterwaves and the formation of a light distribution pattern by the operationof the rotating reflector 26. That is, the obstruction detector 2100 andthe vehicle headlight 10 are integrated.

Next, FIG. 42( a) is a view schematically showing the focal length of amillimeter wave and the focal length of visible light when theprojection lens is made of polycarbonate, and FIG. 42( b) is a viewschematically showing the focal length of a millimeter wave and thefocal length of visible light when the projection lens is made ofacrylic.

As illustrated in FIGS. 42( a) and 42(b), focal lengths are differentsince the wavelength of a millimeter wave is different from that ofvisible light even though the same projection lens is used. Further, theLEDs 28 a and 28 b are provided so that the positions of the virtualimages of the LEDs (the positions of the secondary light sources) formedby the rotating reflector 26 are positioned near the focal point of theprojection lens 130 corresponding to visible light. Furthermore, themillimeter-wave radar 2102 are provided so that the positions of thevirtual images of the LEDs (the positions of the secondary lightsources) formed by the rotating reflector 26 are positioned near thefocal point of the projection lens 130 corresponding to a millimeterwave that is different from the focal point of the projection lenscorresponding to visible light. Accordingly, the millimeter-wave radar2102 and the LEDs 28 a and 28 b can be disposed at the positions of thefocal points suitable therefor without interfering with each other.

Moreover, in the case of a general resin material, the focal pointcorresponding to a millimeter wave tends to be shorter than the focalpoint corresponding to visible light. Accordingly, in the obstructiondetector 2100 according to this embodiment illustrated in FIG. 41, theend portion of the waveguide 2106 is positioned closer to the projectionlens 130 than the LEDs 28 a and 28 b. In other words, the waveguide 2106is provided so that the position of the virtual image of the end portionof the waveguide 2106 (the position of a secondary light source) formedby the rotating reflector 26 is positioned closer to the projection lensthan the focal point corresponding to visible light. Accordingly, forexample, the millimeter-wave integrated circuit 2104 of themillimeter-wave radar 2102 can be disposed more distant from theprojection lens 130 than the LEDs 28 a and 28 b. As a result, light,which is directed to the projection lens 130 from the LEDs 28 a and 28b, is prevented from being blocked by the millimeter-wave integratedcircuit 2104.

The projection lens 130 according to this embodiment is made of a resinmaterial. Since the projection lens is made of a resin material, theweight of the obstruction detector is reduced. In particular, when asemiconductor light emitting element such as a LED is used as a lightsource, the amount of generated heat is small as compared to anincandescent lamp or discharge lamp type light source in the relatedart. Accordingly, a resin material having low heat resistance can beused and costs are reduced. Meanwhile, as long as the projection lens ismade of a material efficiently transmitting millimeter waves and visiblelight, the material of the projection lens is not particularly limited.

The invention has been described above with reference to theabove-mentioned respective embodiments. However, the invention is notlimited to the above-mentioned respective embodiments, and structurewhere the components of the respective embodiments are appropriatelycombined or substituted is also included in the invention. Further, thecombination of the respective embodiments or the order of processingsmay be appropriately changed or modifications such as various changes indesign may be added to each of the embodiments on the basis of theknowledge of those skilled in the art. Accordingly, embodiments to whichthe above-mentioned modifications have been added can be also includedin the scope of the invention.

For example, in the vehicle headlight 10 according to theabove-mentioned embodiment, the three blades of the rotating reflector26 may be colored with red, green, and blue and a white irradiation beammay be formed by the mixture of colors. In this case, it is possible tochange the color of an irradiation beam by controlling ratios of timethat passes while the light of the LED 28 is reflected by the blades ofwhich colors of the surfaces are different. Meanwhile, the coloring ofthe surfaces of the blades is achieved by forming a top coat layerusing, for example, deposition.

Moreover, the vehicle headlight 10 can form spotlight, of which themaximum light intensity is very high, at a desired position by stoppingthe rotating reflector 26 at an arbitrary angle without rotating therotating reflector 26. Accordingly, it is possible to call attention toa specific obstruction (including a person) by irradiating the specificobstruction with bright spotlight.

Further, in the millimeter-wave radar 2102 illustrated in FIG. 41, thewaveguide 2106 functions as both a sending part and a receiving part.FIG. 43 is a schematic view of a millimeter-wave radar according to amodification. As illustrated in FIG. 43, a millimeter-wave radar 2202according to the modification is separately provided with a sendingwaveguide 2106 a and a receiving waveguide 2106 b.

Furthermore, in the lamp unit 20 illustrated in FIG. 1, the rotatingreflector 26 is disposed so as to reflect the light of the LED 28 by theblade that is closer to the convex lens 30 than the rotating part 26 b.FIG. 29 is a view showing the disposition of the rotating reflectoraccording to the modification. As illustrated in FIG. 29, the rotatingreflector 26 according to the modification is disposed so as to reflectthe light of the LED 28 by the blade that is more distant from theconvex lens 30 than the rotating part 26 b. Accordingly, as illustratedin FIG. 29, the rotating reflector 26 can be disposed closer to theconvex lens 30 and the depth (the longitudinal direction of the vehicle)of the lamp unit can be reduced.

Meanwhile, an aspherical lens used in the above-mentioned embodimentdoes not need to necessarily correct a distorted image and may notcorrect a distorted image.

A case where the optical unit is applied to a vehicle lamp has beendescribed in each of the above-mentioned embodiments, but theapplication of the optical unit is not necessarily limited to theapplication to this field. For example, the optical unit may be appliedto lighting equipments of stages or amusement facilities that provideillumination by changing various light distribution patterns. In thepast, the lighting equipments of this field have required large drivemechanisms that change the illumination direction. However, since theoptical unit according to this embodiment can form various lightdistribution patterns by rotating the rotating reflector and turningon/off the light source, a large drive mechanism is not needed.Accordingly, it is possible to reduce the size of the optical unit.

Further, in the optical unit according to the above-mentioned sixthembodiment, the plurality of light sources have been disposed in thelongitudinal direction of the optical axis. However, the plurality oflight sources may be disposed in the up and down direction of theoptical axis. Accordingly, it is possible to perform scanning using thelight of the light source in the up and down direction.

DESCRIPTION OF REFERENCE NUMERALS

-   10: vehicle headlight, 12: lamp body, 14: front cover, 16: lamp    chamber, 18, 20: lamp unit, 22: reflector, 26: rotating reflector,    26 a: blade, 26 b: rotating part, 28: LED, 30: convex lens, 32:    compound parabolic concentrator, 32 a: opening portion.

INDUSTRIAL APPLICABILITY

The invention relates to an optical unit, and may be used for, forexample, a vehicle lamp.

1. An optical unit comprising: a rotating reflector that is rotatedabout a rotation axis in one direction while reflecting light emittedfrom a light source, wherein the rotating reflector is provided with areflecting surface so that the light of the light source reflected bythe rotating reflector while the rotating reflector is rotated forms adesired light distribution pattern.
 2. The optical unit according toclaim 1, further comprising: a light source that is formed of a lightemitting element, wherein the rotation axis is provided substantiallyparallel to a scan plane of an irradiation beam that performs scanningin a left and right direction by rotation.
 3. The optical unit accordingto claim 1, wherein the rotating reflector includes blades that functionas the reflecting surface and are provided around the rotation axis, andthe blades have a twisted shape so that an angle between an optical axisand the reflecting surface is changed in a circumferential directionhaving a center on the rotation axis.
 4. The optical unit according toclaim 3, further comprising: the plurality of blades that are arrangedin a circumferential direction of the rotation axis; and partitionmembers that are provided between the adjacent blades and extend in adirection of the rotation axis, wherein the partition members are formedso as to suppress the incidence of the light emitted from the lightsource upon the reflecting surface of the other adjacent blade when thelight emitted from the light source enters the reflecting surface of oneadjacent blade.
 5. The optical unit according to claim 1, furthercomprising: a projection lens that projects the light reflected by therotating reflector in a light irradiation direction of the optical unit,wherein the projection lens corrects an image of the light sourcedistorted by being reflected on the reflecting surface to a shape closeto the shape of the light source.
 6. The optical unit according to claim5, wherein the light source includes a rectangular light emittingsurface, and each side of the light emitting surface is inclined withrespect to a vertical direction so that an image of the light sourceprojected forward by the projection lens is substantially erected. 7.The optical unit according to claim 1, further comprising: a pluralityof light sources that are formed of light emitting elements, wherein theplurality of light sources are disposed so that light emitted from therespective light sources is reflected at different positions on thereflecting surface.
 8. The optical unit according to claim 7, furthercomprising: a first projection lens that projects light, which isemitted from one light source of the plurality of light sources andreflected by the rotating reflector, in a light irradiation direction ofthe optical unit as a first light distribution pattern; and a secondprojection lens that projects light, which is emitted from the otherlight source of the plurality of light sources and reflected by therotating reflector, in the light irradiation direction of the opticalunit as a second light distribution pattern.
 9. The optical unitaccording to claim 2, wherein the light source includes a lightconcentrating member where a light emitting element is disposed on abottom and a rectangular opening portion is formed, the lightconcentrating member includes light concentrating surfaces that areformed from the bottom toward the opening portion in order toconcentrate the light of the light emitting element, and the lightconcentrating surfaces are formed so that the heights of end portions ofthe opening portion in a longitudinal direction of the opening portionare higher than the heights of end portions of the opening portion in awidth direction of the opening portion.
 10. The optical unit accordingto claim 1, wherein the optical unit is formed so as to be used for avehicle lamp.
 11. An optical unit that is used for a vehicle lamp, theoptical unit comprising: a heat dissipation part that radiates heat of alight source; and a cooling fan, wherein the cooling fan includes bladesthat form a light distribution pattern by reflecting light, which isemitted from the light source, forward and causes convection near theheat dissipation part.
 12. A vehicle monitor comprising: an optical unitthat forms a light distribution pattern by scanning an irradiation beamto the front of a vehicle; a camera that takes an image of a region infront of the vehicle; and a determining device that determines whether areflective body reflecting the irradiation beam is present in a partialregion on the basis of an image that is taken by the camera when thepartial region included in the light distribution pattern is irradiatedwith the irradiation beam and an image that is taken by the camera whenthe partial region is not irradiated with the irradiation beam.
 13. Thevehicle monitor according to claim 12, wherein the optical unit scans anirradiation beam so that a region irradiated with an irradiation beamvaries at each of the timing of plural times of imaging that areperformed by the camera.
 14. A vehicle monitor comprising: a pluralityof optical units that form a light distribution pattern by scanningirradiation beams to the front of a vehicle; a camera that takes animage of a region in front of the vehicle; and a determining device thatdetermines whether a reflective body reflecting the irradiation beam ispresent in a partial region on the basis of an image that is taken bythe camera when the partial region included in the light distributionpattern is irradiated with the irradiation beam and an image that istaken by the camera when the partial region is not irradiated with theirradiation beam.
 15. The vehicle monitor according to claim 14, whereineach of the plurality of optical units scans an irradiation beam so thata region irradiated with irradiation beams varies at each of the timingof plural times of imaging that are performed by the camera.
 16. Thevehicle monitor according to claim 14, wherein assuming that the numberof times of scanning of a first optical unit of the plurality of opticalunits is represented by A1 (times/s), the number of times of scanning ofa second optical unit of the plurality of optical units is representedby A2 (times/s), the number of times of imaging of the camera isrepresented by D (times/s), and m and n are natural numbers, thefollowing expressions (1) and (2) are satisfied:mD<A1<(m+0.5)D or (m+0.5)D<A1<(m+1)D  Expression (1)nD<A2<(n+0.5)D or (n+0.5)D<A2<(n+1)D  Expression (2).
 17. The vehiclemonitor according to claim 13, wherein assuming that the number of timesof scanning of the optical unit is represented by A [times/s], scanningspeed is represented by B [deg/s], the width of an irradiation beam isrepresented by C [deg], and the number of times of imaging of the camerais represented by D [times/s], an expression C≦(decimal part ofA/D)×(B/A)≦(B/A)−C is satisfied.
 18. The vehicle monitor according toclaim 12, wherein the optical unit includes a rotating reflector that isrotated about a rotation axis in one direction while reflecting lightemitted from a light source, and the rotating reflector is provided witha reflecting surface so that the light of the light source reflected bythe rotating reflector while the rotating reflector is rotated forms adesired light distribution pattern.
 19. The vehicle monitor according toclaim 18, further comprising a controller that controls the rotationalspeed of the rotating reflector.
 20. An obstruction detector comprising:an invisible-light radar; a rotating reflector that is rotated about arotation axis in one direction while reflecting invisible light sentfrom the invisible-light radar; and a projection lens that focuses theinvisible light reflected by the rotating reflector and projects theinvisible light to a surrounding region, wherein the rotating reflectoris provided with a reflecting surface so that a surrounding region isscanned with the invisible light reflected by the rotating reflectorwhile the rotating reflector is rotated.
 21. The obstruction detectoraccording to claim 20, further comprising: a light source that is formedof a light emitting element, wherein the rotating reflector is providedwith a reflecting surface so as to form a desired light distributionpattern in front of a vehicle by reflecting light emitted from the lightsource while being rotated, and the projection lens projects the light,which is reflected by the rotating reflector, in a light irradiationdirection.
 22. The obstruction detector according to claim 21, whereinthe invisible-light radar is a millimeter-wave radar, the light sourceis provided so that the position of a virtual image formed by therotating reflector is positioned near a focal point of the projectionlens corresponding to visible light, and the millimeter-wave radar isprovided so that the position of a virtual image formed by the rotatingreflector is positioned near a focal point of the projection lenscorresponding to a millimeter wave that is different from the focalpoint of the projection lens corresponding to visible light.
 23. Theobstruction detector according to claim 22, wherein the millimeter-waveradar includes a waveguide, and the waveguide is provided so that theposition of a virtual image of an end portion of the waveguide formed bythe rotating reflector is positioned closer to the projection lens thanthe focal point corresponding to visible light.
 24. The obstructiondetector according to claim 20, wherein the projection lens is made of aresin material.